EE (SOLUTION)
199 v
A delta 3 - phase, 4 - wire secondary 230/115 v would have a high - leg to neutral voltage of ____
1,000
A lamp produces an illumination of 10 lux at a point 10 m directly below it. What is the luminous intensity of the lamp?
30 V
A 1 m long conductor is moved in a field of density 1 Wb/m^2 at a velocity of 30 m/s. What is the emf induced if the motion is perpendicular to the field?
41.6 sec
A 1.5 MΩ resistor is connected in series with a 20 μF capacitor. The voltage source is 120 volts dc. Determine the time at which the voltage across the capacitor is 75% of the source voltage.
100,000 Ω
A 100 km transmission line has a 1,000 ohms shunt reactance. What is the per km shunt reactance?
6,400 W
If copper loss of a transformer at 7/8th of full-load is 4,900 W, then what is its full-load copper loss?
120 Hz
If the line frequency is 60 Hz, the output frequency of a bridge rectifier is ____
220
Two 500-W lamps connected in series across a 220-v line draw 1 A. The total power consumed is ____ watts.
0.81 x 10^-4 H
An air cored toroidal coil has 450 turns and a mean diameter of 300 mm and a cross - sectional area of 300 mm^2. Determine the self - inductance of the coil
110 A
An 8-pole triplex wave-wound armature carries a total of 660 amperes. If there are 8 brush arms, calculate the current in each armature conductor.
3n^2 - 3n + 1
An ACSR conductor has an (n-1) layers around its single center strand, the total number of strands will be
49.7 A
An alternating current is represented by i = 70.7 sin 520t. Determine the value of the current 0.0015 second after passing through zero and increasing positively
63.7 V
An alternating voltage is given by v = 100 sin 314t volts. Its average value will be ____.
0.863 Ω
An aluminum cable has 10 identical strands, a length of 1500 m and a diameter of 2.50 mm each. What is the resistance of the cable?
1.56 mm
An aluminum wire has a diameter of 2 mm. What must be the diameter of copper wire of the same resistance and length as aluminum?
47
An amplifier has an output of 50 watts. What is its output in dBm?
3,000
An electromagnet has an air gap of 3 mm and the flux density in the gap is 1.257 Wb/m². Calculate the ampere-turns required for the gap.
1.25 x 10^14 electrons
An equal number of electrons is placed on two metal spheres 3 cm apart in air. How many electrons are on each sphere if the resultant force is 4 kN?
873
An induction motor with 8 poles, 60 Hz is operated with a slip of 3%. Calculate the rotor speed.
50
Branch circuit larger than ____ amperes shall only supply nonlighting outlet load
4.32 v
Calculate the average voltage generated in a six - turn - full - pitch coil of a 25 - cycle alternator if the flux per pole is 7.2 x 10^5 maxwells
354 pF
Calculate the capacitance of a parallel plate capacitor having 20 cm x 20 cm square plates separated by a distance of 1 mm. Assume the dielectric medium to be air with permitivity of 8.85 x 10^-12 F/m
3 N
Calculate the force developed per meter length between two current-carrying conductors 10 cm apart and carrying 1,000 A and 1,500 A currents respectively
1.7036r
Determine the GMR of a three-equal strands conductors in vertical formation in terms of r of an individual strand.
23.8 mH
Determine the total inductance of a single - phase overhead transmission line of 10 km long. The diameter of each conductor is 0.8 cm and the distance between them is 1.2 meters
44
If stator voltage of a SCIM is reduced by 25 % of its rated voltage, torque developed is reduced by ___ percent of its full-load value.
27.47
Suppose that the consumption of energy in a certain country has a growth rate of 4 percent per year. In how many years will the energy consumption be tripled?
$1.50
Suppose the electric company charges 10 cents per kW-h. How much does it cost to use a 125 W lamp 4 hours a day for 30 days?
6 Ω
Two 6 - ohm resistors are connected in series. When a resistor R is connected in parallel with one of them, the total resistance is 9 ohms. What is the value of R?
25 MHz
Wavelength is the distance travelled by an electronic wave during the time of one cycle. Given a wavelength of 12 meters, what is the frequency
23,900 N
What is the force required to separate two surfaces with contact area of 150 sq. cm when the flux density is 2 Tesla normal to the surfaces?
3
What is the maximum number of conductors in a raceway that does not need to be derated?
4.17%
You have 120 volts at the panel and 115 volts at the load. What is the percentage voltage drop?
1,125 rpm
a 4-pole, 50-cycle, three-phase induction motor has a blocked-rotor reactance per phase that is four times the rotor resistance per phase. At what speed will the motor develop maximum torque?
200
a light source is located 2 m from a surface produces an illumination of 50 lux on that surface. Find the intensity of the light source in candela.
1000
10^13 ergs/sec is equal to how many kW?
2 A
A 10 KVA, 200/400 v, 1 - phase transformer is operated with open circuited secondary. Find the primary current
125 a
A 100 HP, 440 volt, three-phae, 60 Hz induction motor operates with 92 percent efficiency, 0.85 power factor , at rated load. What is the current of the motor?
25
A 100 kVA, 20/5 kV transformer has an equivalent impedance of 10%. Calculate the impedance (in ohm/s) of the transformer referred to the 5 kV side.
120,000 Ω
A 100 km transmission line has a 1,200 Ω shunt reactance. What is the per km shunt reactance?
11.56
A 100 watts 230 volts gas fitted lamp has a mean spherical candle power of 92. Find its efficiency in lumens per watt.
5 ms
A 100 μF capacitor, carrying an initial charge of 500 μC is discharged through a 50 Ω resistor. Determine the time it takes the capacitor to discharge to 184 μC charge.
1,387.5 rpm
A 110 - volt shunt motor has an armature resistance of 0.8 ohm and a field resistance of 220 ohms. At full load the motor takes 10 amperes and the speed is 1,200 rpm. At what speed must this motor run as a generator to deliver 10 amperes to an external circuit at 110 volts?
0.2609
A 115 kV three - phase transposed transmission line is composed of 2 - ACSR 336, 400 cmil, 30/7 Oriole conductors per phase with horizontal configuration: D_12 = 7 ft, D_13 = 14 ft. The line spacing is measured from the center of the bundled conductors. The distance between the conductors of the bundle is 6 inches. The conductors have a diameter of 0.741 inch and a GMR of 0.022255 ft. Find the capacitance per phase for 20 km of the line in microfarads
0.747
A 12 - KVA load A operating at 0.70 p.f. lagging and a 10 - KVA load B operating at 0.80 p.f. lagging are connected in parallel and supplied by a 440 v, 60 Hz generator. Determine the system power factor
727.5 rpm
A 12 - pole, 3 - phase alternator driven at a speed of 500 rpm supplies power to an 8 - pole, 3 - phase induction motor. If the slip of the motor at full - load is 3%, calculate the full - load speed of the motor
360 watts
A 120 - volt battery having an internal resistance of 0.5 Ω is connected through line resistance of 9.5 Ω to a variable load resistor. What maximum power will the battery deliver to the load resistor?
360 W
A 120 volts battery having an internal resistance of 0.5 Ω is connected through line resistance of 9.5 Ω to a variable load resistor. What maximum power will the battery deliver to the load resistor?
0.079
A 13.8 kV/440 v, 50 kVA single - phase transformer has a leakage reactance of 300 ohms referred to the 13.8 kV side. Determine the per unit value of the leakage reactance for the low voltage base
72
A 220 v bulb draws a current of 10 A. How much charge in kilocoulombs will pass through the bulb in two hours period?
3,484.8
A 220 v, 3 - phase supply has a balanced delta connected load with impedance of 15 + j20 ohms/phase. What is the total real power of the load in watts?
3,495
A 220 v, 3 - phase, 4 - wire abc system supplies unbalanced wye - connected resistances of 10 Ω, 15 Ω and 20 Ω. Determine the total power of the system in watts
40 μF
A 24-V source and two capacitor are connected in series. If one capacitor has 20 μF capacitance and has 16 V across it, what is the capacitance of the other capacitor?
0.3775
A 3-phase circuit 60 HZ, 230 kV transposed transmission line is composed of two 1,272 MCM 54/19 conductors per phase with horizontal configuration. The bundle conductors are 50 cm in distance while phase spacing between the centers of the bundle is 10 meters. if the GMR of the ACSR conductors is 0.0466 ft., find the inductive reactance in ohm/km/phase of the transmission line?
2.0 V
A 3-Ω and a 1.5-Ω resistor are wired in parallel and the combination is wired in series to a 4-Ω resistor and a 10-V emf device. The potential difference across the 3-Ω resistor is:
250 v
A 300-kW 250-volt 8-pole generator has a simplex lap winding. Determine the voltage generated per path.
3.46 ohms
A 34.5 kV feeder line is 5 miles long. The conductors are spaced 4 - feet horizontally. The conductor is 4/0 copper with GMR of 0.01688 ft. What is the reactance?
0.0168 ft
A 34.5 kV feeder line is 5 miles long. The conductors are spaced 4 feet horizontally. If the inductive reactance of the line is 3.46 ohms per phase, what is the self GMD of each conductor?
j2.38 pu
A 345 KV transmission line has a series impedance of (4 + j60) Ω and a shunt admittance of j2 x 10^-3 S. Using 100 MVA and the line voltage as base values, calculate the per unit shunt admittance of the line
18 Ω
A 36 Ω resistor is connected in parallel with an unknown resistor R. Their combination is then connected in series with a 12 Ω resistor. Find the value of R such that the power drawn by the parallel combination of 36 Ω and R is equal to the power in the 12 Ω resistor.
240 v
A 4 - pole dc generator has a total of 600 conductors in its lap wound armature. The flux per pole is 10^6 lines. Determine the generated emf if it is driven at 2,400 rpm
907 W
A 4,400 v, 60 Hz transformer has core loss 0f 840 watts, of which one-third is eddy current loss. what is the core loss when the transformer is connected to a 4,600 v, 60 Hz source?
1,710 rpm
A 4-pole induction motor running with 5% slip is supplied by a 60-Hz synchronous generator. Determine the speed of the motor.
120 V
A 4-pole lap wound armature has 400 conductors and a flux per pole of 25 mWb. The emf generated, when running at 600 rpm, will be?
11 Ω
A 4-pole wave wound generator has 220 coils of 10 turns each. The resistance of each turn is 0.02 Ω. find the resistance of armature winding.
40.4
A 4-pole, 3-phase induction motor has a wye-connected stator winding and runs on a 220 v, 60 Hz supply. The rotor resistance and standstill leakage reactance are 0.1 and 0.9 ohm/phase, respectively. The ratio of rotor to stator turns/phase is 2/3. Calculate the torque developed in N-m when running with a slip of 4%
3.33 MS/m
A 40 - m metallic conductor of cross - sectional area 1 mm^2 has a resistance of 12 Ω. Calculate the conductivity of the metal
1.51 A
A 40 microF capacitor is supplied with a voltage of v(t) = 100 sin 377t. What is the current at t = 0?
64.15
A 40 ohm resistor and a pure capacitor are connected in parallel across a 230 v, 60 Hz ac supply. The total current taken from the supply is 8 A. Find the capacitance of the capacitor in microF
3,300 A
A 5 MVA, 13.8/0.48 kV, 5% impedance transformer is tapped at 13.8 kV line where the Thevenin's equivalent impedance is 0.5 ohm. Determine the fault current at the primary for a three - phase fault at the secondary
160 kW
A 5,000 kVA synchronous condenser operates with a leading p.f. of 0.032. The losses are 160 kW. What is the power input to the motor?
94.92%
A 50 - kVA single - phase transformer has on full - load a copper loss of 560 watts and iron loss of 500 watts. Calculate the efficiency at 25% of full - load for a power factor of 0.8 lagging
6 amperes for 10 hours
A 60 ampere hour battery has 6 ampere discharge rate. it will provide a current of?
0.106
A 7.5 MVA, 69/13.8 kV, 3 phase transformer has 8% impedance. What is teh per unit impedance at 10 MVA base?
188.4 MWHR
A certain electric generating station has an efficiency of 25%. If the coal consumption is 4,500 kg/hr and calorific value of coal is 6,000 kcal/kg, find the total energy produced per day
0.20
A conductor has an area of 40,000 CM. What is the diameter of this conductor in inches?
5.39 cm
A hydroelctric generating station is supplied from a reservoir of capacity 6,000,000 m^3 at a head of 170 m. Assume hydraulic efficiency of 80% and electrical of 90%. The fall in the reservoir level after a load of 15 MW has been supplied for 3 hours, if the area of the reservoir is 2.5 km^2 is closest to ____
2.044 x 10^5
A hydroelectric generating station is supplied from a reservoir of capacity 5 x 10^6 m^3 at a head of 200 meters. Find the total energy available in KWHR if the overall efficiency is 75%
2.044 x 10⁶ kwhr
A hydroelectric generating station is supplied from a reservoir of capacity 5 x 10⁶ cubic meters at a head of 200 meters. Find the total energy available in KWHR if the overall efficiency is 75%.
156.7 Oersted
A magnetic circuit consists of silicon steel 3,000 permeability of 10 cm length and cross - section of 1.5 square cm and an air gap of the same cross - section and of 2 cm length. A 0.5 ampere current flows through 500 turns. What is the field intensity at the air gap?
1.257 mT
A magnetizing force of 1,000 AT/m will produce a flux density of ___ in air.
20 kΩ/V
A meter has a full - scale current of 50 microA, what is its sensitivity?
120,000 rad/sec
A parallel RLC circuit has te following properties: R = 6 Ω, bandwidth = 1,000 rad/sec, Q = 120. Determine the resonant frequency
0.12 v
A piece of conductor 10 cm long moves across a magnetic field of 10,000 gauss at a velocity of 120 cm/sec. What voltage appears across the conductor?
120 mV
A piece of conductor 10 cm long moves across the magnetic field of 10k gauss at a velocity of 120 cm/s. What is the voltage across the conductor?
0.1 A
A potentially lethal electric current is on the order of _____
105,500 kW
A power plant consumes 100,000 lbs of coal per hour. The heating value of the coal is 12,000 BTU per lb. The overall plant efficiency is 30%. What is the kW output of the plant?
12,250 kW
A power plant gets water from a dam from a height of 100 meters at the rate of 1,000 cubic meters per minute. If the overall efficiency of the plant is 75%, what is the kW output of the plant?
75%
A power plant gets water from a dam from a height of 122.45 m at the rate of 1,000 cubic meters per minute. If the output of the plant is 15,000 kW, what is the plant efficiency?
57.08%
A power plant has a peak demand of 80 MW and a connected load of 150 MW. It produces a total power of 400,00 MWHR annually. What is the annual load factor of the plant?
7.35 A
A pulsating direct current has a constant magnitude of 9 A for 0.02 sec and is 0 for 0.01 sec. The cycle is then repeated. What is its effective value?
4 ohms
A resistance of 4 ohms is connected across 100V supply. When another resistor 'R' ohms is connected in parallel with 4 ohms, the total current taken from supply was found to be 50A. The value of resistance 'R' is?
6 Ω
A resistance of 6 Ω is connected in parallel with another resistor R across a 120 v supply. The total current taken from the supply was found to be 40 A. What is the value of resistance R?
40%
A room 8 m x 12 m is lighted by 15 lamps to fairly uniform illumination of 100 lumens per square meter. What is the coefficient of utilization if the output of each lamp is 1,600 lumens?
50 Hz
A series RLC circuit consists of 5 Ω resistor, a 0.2 H inductor and a 50 microF capacitor. Compute the resonant frequency
10
A three - phase 60 Hz transposed 230 KV transmission line has a horizontal configuration of D_ab = D and D_bc = D and D_ac = 2D. The line reactance is 0.486 ohm per km. The conductor GMR is 2.0 cm. What is the phase spacing D?
142.2 microF
A three - phase induction motor delivers 100 HP while operating at 80% efficiency and a power factor of 0.75 lagging from 480 V lines. A delta connected power factor correction capacitor is to be installed to improve the overall power factor to 0.90 lagging. Determine the required capacitance per phase
2.7 Hz
A three - phase induction motor has a nameplate speed of 1,720 rpm. What is the rotor frequency?
87.63 kW
A three - phase induction motor is taking 40 kW, the slip being 4% and stator losses amount to 800 watts. Calculate the total power developed
57.5 A
A three - phase motor is rated 50 HP, 440 volts and 85% power factor. What is its rated current?
0%
A three - phase synchronous motor runs at full - load speed of 1,200 rpm. If the load is reduced to one - half of rated, calculate its speed regulation
7,194 w
A three - phase, 60 Hz, 6 - pole induction motor delivers 25 HP at 1,150 rpm. If the rotor copper loss is 300 watts, what is the rotor power input?
157.1 rad/sec
A two-pole alternator is running at 1,500 rpm, what is the angular velocity?
9.4
A uniform source of light gives 1,884 lumens and is suspended 4m above the center of a floor 3 meter square. Find the illumination in Im/m^2 at the floor level immediately below the lamp.
55.6 min
A walkman has 4 - AA batteries. The combination has a capacity of 200 watt - sec. How long will it take to discharge if walkman consumes 10 mA at 6 v?
0.60 lagging
A washing machine is, in effect, an R-L circuit. If the machine take 311 W and 4.5 A from a 115-V source when operating normally. Find its power factor.
58.3 kW
A wind generator with an efficiency of 0.85 has a blade diameter of 20 m. If the wind velocity is 30 km/hr, how much power is obtainable from the generator?
54.87
A wind generator with an efficiency of 80% has a blade diameter of 20m. If the wind velocity is 30 km/hr, how much power in KW is obtained from the generator?
26 mH
An inductive coil consumes active power of 500 W and draws 10 A from a 60 Hz ac supply of 110 V. What is the coil inductance?
4.36 KWHR
Find the amount of electrical energy expended in raising the temperature of 45 liters of water by 75 degree C. Assume a heater efficiency of 90%
5.10 x 0^-6 mho/mi to neutral
Find the capacitive susceptance per mile to neutral of a single - phase line operating at 60 Hz. The conductor is Partridge with an outside diameter of 0.642 inch and spacing is 20 ft between centers
40 V
Find the emf induced on a 0.4 H inductor if the current changes from 10 A to 30 A in 0.2 second
4
In a 10 - pole synchronous machine, 20 electrical degrees are equivalent to how many mechanical degrees?
32.93 pu
In a 13.8 kV, 10 MVA base three-phase system, a phase to phase fault occurs. If the Thevenin's equivalent impedance of the system is 2.63%, what is the per unit fault current?
540
In a 15-v battery supplies 10 a, find the amount of energy in KJ delivered in one hour.
0.94 v
In a 4 - pole dynamo, the flux per pole is 15 mWb. Calculate the maximum emf induced in one of the armature conductors if armature is driven at 600 rpm
60
In a 6-pole alternator how many mechanical degrees is the equivalent of 180 electrical degrees?
0.9%
In a certain country, the peak power demand for year 2005 is 9,287 MW and by year 2014 it is estimated to be 10,064 MW. Calculate the growth rate
232.8 v
In a generator, if the voltage regulation is 5.5% and the full - load voltage is 220 volts, what is the no - load voltage equal to?
2,000 amps
In a short circuit study, the positive, negative and zero sequence impedances are 0.25 p.u., 0.25 p.u. and 0.3 p.u., respectively. The base MVA is 100. Determine the fault current for a three phase fault at the 115kV level
0.94
In an ACB sequence balanced 3ϕ system, the angle between the line voltage and the line voltage and the line current 50°, what is the lagging power factor of the system?
0.856
Power in balanced 3 - phase system is measured by the two - wattmeter method and it is found that the ratio of the two - wattmeter readings is 2 is to 1. What is the power factor of the system?
22.62 v
The active length of each conductor placed in a DC generator armature is 0.4 m. The armature is rotated at a speed of 1,800 rpm in a magnetic field of average flux density 1.2 T. The diameter of the armature is 0.5 m. Find the emf induced in the conductor when it cuts the magnetic field at right angles
2.5 mH
The core of a certain magnetic circuit has a length of 5 cm and the inductance of the coil is 10 mH. What is the inductance of the same if the number of turns is reduced to one half of the original? All other factors are unchanged
4.36 ms
The current in a coil decays as follows: when t = 0.002 sec, the current is 10 mA; when t = 0.006 sec, the current drops to 4 mA. The time constant of the coil is ____
6
The nameplate speed of a 60 Hz, 3 phase induction motor is 1,175 rpm. What is its number of poles?
10.24
The net energy required for a certain country in year 2010 was approximately 3 x 10^6 GWHR. What is the equivalent of this energy in quad?
106 V
A 110 V DC motor draws an armature current of 16 A. If the armature resistance is 0.25 Ω, compute for the back emf
0.3174 Ω
A 13.8 kV/480 v, 30 - MVA three - phase transformer has a 0.03 pu resistance and 0.04 pu reactance. What is the transformer actual impedance referred to the primary?
1,200 W
A 15 hp motor operates at an efficiency of 87.5 percent at full - load. If the stray power loss is approximately one - fourth of the total loss, calculate the copper loss
93 ~ 92.75
A 15 hp, 460 V, 60 Hz, 6 pole, 3 phase induction motor has full load slip of 4 %. Find the full-load torque in N-m.
93
A 15 hp, 460v 60 Hz, 6 pole, 3 phase induction motor has full-load slip of 4%. Find the full-load torque in N-m.
60 degree
A 15 Ω resistor connected in series with an inductor has an equivalent impedance of 30 Ω with an unknown angle. Find the power factor angle in degrees
98.28
A 2 MVA, 13.2 kV/440 V, 60 Hz, 3 phase transformer has a per unit impedance of 0.01 + j0.08. Calculate the percent efficiency at full-load and 0.8 p.f. lagging if core loss is 8 kW.
13.5 mJ
A 2-H inductor, a 430-Ω resistor, and a 50-V source have been connected in series for a long time. What is the energy stored in the inductor?
60.65 A
A 20 KV/7.87 KV autotransformer has a secondary line current of 100 A. What is the current in the common winding?
0.033 pu
A 20 kVA, 2000/220 v, single - phase transformer has a primary resistance of 2.1 Ω and a secondary resistance of 0.026 Ω. The corresponding leakage reactances are 2.5 Ω and 0.03 Ω. Determine the transformer per unit impedance
1039 W
A 20 kW, 100 V shunt generator is operated at rated load. If the driving engine is dveloping 30 HP, determine the iron and friction losses. Armature resistance is 0.05 ohm and field resistance is 50 ohms.
0.98 - j1.47 kVA
A 20 μF capacitor and a parallel 200 Ω resistor draws 4 A at 60 Hz. Find the power consumption.
159.2 Hz
A 20 μF capacitor is in parallel with a practical inductor represented by L= 1 mH in series with R= 7Ω. Find the resonant frequency of the parallel circuit
141.4
A 200 kVA transformer has an iron loss of 1 kW and full-load Cu loss of 2 kW. Its load kVA corresponding to maximum efficiency is ___ kVA.
9.16 cos 377t
A 24.6 microF capacitor stores an energy W = 12 sin^2 377t J. Find the current through it
92.7%
A 240 v dc generator supplies 100 amperes at maximum operating efficiency. if the constant losses are 950 watts at rated output, what is the maximum efficiency?
12.8
A 25 KVA transformer supplies a load of 12 kW at a power factor of 0.6 lagging. Find the maximum KVA load at a power factor of 0.866 leading can be added without overloading the transformer
80%
A 25 Ω resistor connected in series with a coil 50 Ω resistance and 150 mH inductance. What is the power factor of the circuit?
0
A 3 - phase, 4 - pole induction motor with open circuited rotor is connected to a 400 - v, 50 Hz, 3 - phase supply. The motor will run at ____ rpm
4,165 W
A 3 - phase, 6 - pole, 50 Hz induction motor develops 3.73 kW at 960 rpm. What will be the stator input if the stator loss is 280 watts?
0.0104
A 3 - phase, 60 Hz transposed transmission line is arranged horizontally with distances D_12 = 5 ft, D_23 = 5 ft and D_13 = 10 ft. The outside diameter of the conductors is 0.721 inch and with GMR of 0.0243 ft. Determine the capacitance per phase of the line in microfarad per kilometer
32.4 A
A 3 phase motor takes 10 kva at 0.6 pf lagging from a source of 220-V. It is in parallel with a balanced delta-load having 16 Ω resistance and -j12 Ω reactance in series in each phase. Find the total line current of the combination.
86.4 mJ
A 3 μF capacitor is initially 50% charged. What will be the maximum possible energy stored if connected across a 240 volt source?
1 μH/m
A 3Φ transmission line has two aluminum conductors in bundle. The self GMD of each conductor is 8.90 mm and the distance between the conductors and phases is 40 cm and 9 m, respectively. What is the inductance of the line per phase?
1μH/m
A 3ϕ transmission line has two aluminum conductors in bundle. The self GMD of each conductor is 8.90 mm and the distance between the conductors and phases is 40 cm and 9 m, respectively. What is the inductance of the line per phase?
46 A
A 4 - pole shunt motor develops 20 lb - ft of torque when the flux per pole is 700,000 maxwells. If the armature winding has 264 conductors and is wound wave, calculate the total armature current
11
A 4 - pole wave wound generator has 220 coils of 10 turns each. The resistance of each turn is 0.02 Ω. Find the resistance of armature winding.
19.51 N - m
A 4 - pole, three - phase 50 Hz induction motor develops a maximum torque of 20 N - m at 1,440 rpm. Obtain the torque exerted by the motor at 5% slip
8
A 4 pole dc machine is wound duplex lap. Find the number of parallel paths.
23.8 mWb
A 4 pole lap winding motor with 16 slots, 42 conductors per slot, 480 v runs at 1,800 rpm. Find the flux produced per pole
48.9
A 400 volt 50 Hz star connected induction motor takes a line current of 50 amperes at p.f. of 0.8 lagging. Three mesh connected capacitors are connected to raise the p.f. to 0.9. Find the value of each capacitor in microfarads
242 N - m
A 42 kW, 400 V dc shunt motor has a rated armature current of 100 A at 1,500 rpm. The resistance of the armature is 0.2 ohm. Find the internal torque developed
0.107
A 440 V, 60 Hz, 6 pole, 3 phase induction motor has rotor input power of 33 kW at rated voltage and frequency. Under this condition, the rotor emf makes 126 complete cycle/minute. Find the rotor resistance in ohm/phase if the rotor is 60 A/phase.
1.7 Ω
A 440 v, 70 HP shunt motor has an armature of 0.185 Ω and field resistance of 350 Ω. The current drawn by this machine is 135 A at full - load. If this machine is to deliver torque equal to 175 percent of that at full - load, what would be the resistance of its starter?
18.97 KVA
A 440 v, three - phase source supplies a wye - connected 10 KVA load at 0.8 lagging power factor and a delta - connected 10 KVA unity power - factor load. Calculated the total apparent power input to the two loads
90%
A 50 HP, 550 V shunt-wound motor draws a line current of 4.5 A at no-load. The shunt field resistance is 275 ohms and the armature resistance exclusive of the brushes is 0.3 ohm, the brush drop at full-load is 2 V. At full-load, the motor draws a line current of 84 A. Calculate the efficiency at full load.
35.71
A 50 MVA, 11 kV, 3 - phase alternator supplies full - load at a lagging power factor of 0.7. What would be the percentage increase in earning capacity if the power factor is increased to 0.95?
8.1 x 10^5 lb
A 50 MW coal - fired power plant has an average heat rate of 11,000 BTU/kWHR. Coal has a heating value of 13,000 BTU per pound. The plant has a load factor of 80%. How much coal is burned per day?
15 v
A 50 cm long conductor is moved in a field of density 1 Wb/m^2 at a velocity of 30 m/s. What is the emf induced if the motion is perpendicular to the field?
97.32%
A 50-kVA, 7,620/240 v, single-phase transformer has rated core loss of 350 watts and rated full load copper loss of 800 watts. The transformer is 50% loaded for 12 hours at 0.8 p.f lagging. The rest of the day, it is disconnected from the source. Calculate the all-day efficiency of the transformer.
27.83 kW
A 500 - KVA alternator operates at 80% of full - load with an efficiency of 92 percent. If the load power factor is 0.8, calculate the total loss
98.7
A 500 KVA, 34.5/13.8 kV, 3 phase transformer is delta-wye connected. The primary and secondary winding resistances are 35 ohms and 0.876 ohm per phase, respectively. Calculate teh percent efficiency at full-load and unity power factor if core loss is 3 kW.
116.25
A 500 MCM ACSR cable has 37 strands. Determine the diameter in mils of each strand
725 W
A 500 volts 1 - phase synchronous motor is taking 50 amperes at a p.f. of 0.8 leading. The output is 25 HP and the effective resistance of the armature is 0.25 ohm. Find the iron and friction losses
50 A
A 6 - pole lap wound dc generator has 240 armature conductors, a flux of 0.04 Wb per pole and runs at 1,500 rpm. If the armature resistance is 0.8 Ω, determine the current through each conductor
160 N - m
A 6 - pole, 50 Hz, three - phase induction motor has a maximum torque of 200 N - m when it is running at a speed of 900 rpm. The resistance of the rotor is 0.25 Ω. Neglecting stator impedance, determine the torque at 5% slip
512.4 V
A 6 pole, 3 phase, 60 cycle alternator has 12 slots per pole and four conductors per slot. The winding is 5/6 pitch. There are 2,500,000 Maxwells entering the armaturefrom each North Pole, and this flux is sinusoidally distributed along the air gap. Thearmature coils are all-connected in series. Th winding is wyw-connected. Determine the open circuit emf of the alternator.
24.5 mH
A 6 Ω resistor is connected in series with an inductor L across a 110 v, 60 Hz source and draws a current of 10 A
45
A 60 Hz, 4 pole, 3 phase induction motor has a slip of 2.5%. What is the slip speed in rpm?
0.7
A 60 Hz, 4 pole, 3 phase wound rotor induction motor has rotor resistance and standstill leakage reactance of 0.1 and 0.8 ohm/phase respectively. How much additional resistance must be inserted in the rortor in ohms/phase so that the motor has maximum starting torque?
95.90%
A 69 KV, three - phase short transmission line is 16 km long. The line has a per phase series impedance of 0.125 + j0.4375 ohm per km. Determine the transmission efficiency when the line delivers 70 MVA, 0.80 lagging power factor at 64 KV
21.15 MW
A 75 MW power plant has an average load of 35,000 KW and a load factor of 65%. Find the reserve over peak
42 tons
A 75 MW steam power station uses coal of calorific value of 6,400 kcal/kg. Thermal efficiency of the station is 30% while electrical efficiency is 80%. Calculate the coal consumption per hour when the station is delivering its full output
422 W
A 75 kVA, 13,200/240, 60 Hz, single-phase transformer has 1% resistance and 3% reactance. Find the copper loss of the transformer at 3/4 of full-load and unity power factor
247.5
A 75 kVA, single phase transformer has secondary winding impedance of Z_s = 0.02 + j0.08ohm. Calculate the secondary induced voltage in volts when the transformer is supplying full load at unity power factor and 240 v.
774
A 9.6 KW, 240 volts shunt generator having an armature resistance of 0.10 ohm and a shunt field resistance of 240 ohms, delivers full load at rated voltage and 800 rpm. The machine is now run as a motor while taking 250 v. Neglect the brush contact drop, what is the speed of the motor?
0
A DC voltmeter is connected across as AC source of 220 V, 60 Hz. What will be the reading of the voltmeter?
30 Ω
A balanced delta connected load draws 10 A of line current and 3 KW at 220 v. Determine the value of resistance of each phase of the load
0
A balanced delta connected load draws 100 A line current from a balanced 3 - phase supply. Determine the zero sequence components of the currents
52
A balanced delta connected load of 4 - j3 Ω per phase is fed by a 380 v, 3 - phase system. Find the reactive power in KVAR
38.1 A
A balanced delta load of 3 + j4 Ω per phase is connected to a balanced 110 v source. Find the line current
7,200
A balanced wye - connected load with resistance of 8 ohms/phase and no reactance is supplied nu a 240 v, 3 - phase source. Find the real power of the load in watts
126 x 10^-11 F
A capacitor consists of two metal plates each 40 cm x 40 cm, spaced 6 mm apart. The space between the metal plates is filled with a glass plate 5 mm thick and a layer of paper 1 mm thick. The relative permitivities of glass and paper are 8 and 2, respectively. Calculate the capacitance
200 microF
A capacitor is charge 0.23 watt - second of energy at a voltage of 48 volts. What is its capacitance?
0.621 microF
A capacitor is charged by a dc source through a resistor of one megohm. If in one second, the potential difference across capacitor reaches 80% of its final value, calculate its capacitance
50 μF
A capacitor is charged with 10,000 μC. If the energy stored is 1 joule, find the capacitance.
6 sec
A capacitor is used to charge the lamp of the flash of a camera. If the source voltage is 6 V, how long will it take to charge the capacitor of 10 microF if it takes 10 microA current
15
A capacitor of 0.0005 μF is to be formed from tin foils, measuring 3 cm by 1.5 cm. the dielectric to be used is 0.5 mm mica film. Determine the number of tin foils required. The relative permittivity of mica is 4.5.
1,000 v/s
A capacitor of 0.1 microF capacitance charged to a potential difference between plates of 100 v, is discharged through a resistor of 1 mega ohm. Calculate the initial vale of decay of capacitor voltage
277.4 μs
A capacitor of 2μF with an initial charge of q₀ = 100 x 10⁻⁶ coulombs is connected across the terminals of a 100 ohm resistor at t = 0. Calculate the time in which the transient voltage across the resistor drops from 40 to 10 volts.
0.124 J
A capacitor of 40 microF capacitance in series with 2,000 ohms is suddenly connected across a 200 - volt source. What is the energy stored in the capacitor after 0.04 sec?
4 C
A car battery supplies 48 J of energy at 12 v over a certain period of time. Determine the charge moved during this period
183
A certain amount of fuel can be converted into 3 x 10^-3 quads of energy. Assume a 30% overall efficiency for the power plant. If the average load on the power plant over a 24 hours period is 60 MW, how long in day/s the fuel will last?
3.78 x 10^10 kcal
A certain amount of fuel contains 15 x 10^10 BTU of energy. What is the corresponding energy in kilocalories?
42 800
A certain amount of fuel contains 17 x 10¹⁰ BTU of energy. What is the corresponding energy in Gigacalories?
26
A certain copper wire has a resistance of 0.5 Ω when the length is 10 m. What is its diameter in mils?
59.38°C
A certain copper wire has a resistance of 25 ohms at 10°C. Take the temperature coefficient at 10°C to be α = 0.00405°C⁻¹. What must be the maximum operating temperature of the wire if its resistance is to increase by at most 20%?
952 hours
A certain power plant has a reserve capacity above the peak load of 10 MW. The annual factors are load factor = 59%, capacity factor = 41% and use factor = 46%. Determine hours per year not in service.
1
A circuit which has ω_0 = 10^6 rad/sec, C = 10pF and Q = 100, must have a resistance of ____ kΩ
R = 46 Ω ; L = 0.102 H
A coil energized by 120 V at 60 Hz draws a 2-A current that lags the applied voltage by 40°. What are the coil resistance and inductance?
2.5 A/s
A coil having a resistance of 10 Ω and an inductance of 4 H is switched across a 20 V dc source. Calculate the rate of current change when the current reaches 50% of its final steady value.
1.25 sin (ωt + 75.5°)
A coil of 50 resistance and 150 mH inductance is connected in parallel with a 50 microF capacitor. The source voltage is 100 sin (ωt + 30°) v. What is the equation of the line current?
4.58 Ω
A coil of copper wire has a resistance of 5.46 Ω at 75° C. What will be its resistance at 25° C?
12.07
A coil with 40 ohm resistance and 0.02 H inductance and a pure capacitor are connected in parallel across a 60 Hz supply. Find the value of the capacitor in microF if the circuit is resonant
1.6921r
A conductor has four identical strands arranged in diamond configuration. Find the GMR of the conductor in terms of the radius r of each strand
25 v
A conductor of length 1 meter moves at right angle to a magnetic field of flux density 1 Wb/m^2 with a velocity of 25 m/s. What is the induced emf in the conductor?
761 kw
A consumer requires 2 x 10^6 KWHR per year and its yearly load factor is 30 percent. What is its maximum demand?
1.25
A copper conductor with a diameter of 0.10 inch has a resistance of 1 ohm per 1,000 ft. What is the resistance of 200 ft copper wire with a diameter of 40 mils?
4R_1
A copper wire is drawn down such that its length is doubled but the volume remains the same, what is the new resistance of the wire?
30 degree
A current of 10 A is flowing in a flexible conductor of length 1.5 m. A force of 15 N acts on it when it is placed in a uniform field of 2 T. Calculate the angle between the magnetic field and the direction of the current
1 A
A current of 20 A is flowing in an RL series circuit the instant before the switch is opened. If R= 10 Ω and L = 10 H, find the current after 3 seconds has elapsed
P 1,014
A customer owns an old air conditioning unit rated 1/2 HP at 70% efficiency but decided to buy a new one of the same horsepower rating with 85% efficiency and with 2 years warranty. If the usage of new unit is 8 hours per day and 150 days per year, what is the differential cost of energy in one year when the unit cost of energy is P 8.99/kWHR?
4R
A cylindrical copper rod has resistance R. It is reformed to twice its original length with NO change of volume. What is its new resistance?
100
A dc ammeter has an internal resistance of 0.1 Ω. A shunt of 1.01 x10^-3 Ω is connected to the ammeter. What is the multiplier of the set up?
93%
A dc shunt motor develops 15 hp at 120 v. If the effective armature resistance is 0.061 ohm and the field winding draws 2 amperes, what is the overall efficiency?
6.74 A
A dc shunt motor has a nameplate rating of 15 HP, 230 V, 57.1 amperes and 1,400 rpm. The field circuit has a resistance of 115 Ω and the armature circuit resistance is 0.13 Ω. Neglecting the effect of armature reaction, find the no - load line current
224
A delta connected load of 9 + j12 ohms/phase is supplied by a 230 V, 3 - phase source through a line with an impedance of 0.06 + j0.12 ohm per conductor. Find the load voltage in volts
50
A diversity factor of 2 gives a saving of ____% in generating equipment
96
A four pole DC generator with lap winding has 48 slots and 4 elements per slot. How many coils does it have?
75%
A generating plant has a minimum and maximum outputs of 50 MW and 100 MW, respectively. It generates an energy of 1,800,000 KWHR for hours at an average power factor of 90%. What is the load factor of the plant?
10,000
A given capacitor has a capacitance of 100 microF. Calculate its elastance
157 A
A half wave rectified sine wave has an average value of 100 amperes. What is its effective value?
28.75 A
A hermetic motor compressor has a rated load current of 25A. What is the allowable rating for a branch disconnecting means?
100 A
A hermetic motor compressor has a rated load current of 80 A. What is the allowable rating of the branch circuit overload protection of a fuse?
25
A lamp has a luminous efficiency of 11 lm/watt and gives out a luminous flux of 275 lm. What is the wattage of the lamp?
200 lux
A lamp produces an initial illumination of 800 lux over a normally placed screen. If the distance of the lamp from the screen is doubled, what is the new illumination on the screen?
3/4
A lead - acid battery having a 100 Ah capacity is 25% charged. After being charged at 10 A for 5 hours, it will be approximately ____ charged
3,600 watts
A lead storage battery is rated at 12 volts. If the internal resistance is 0.01 Ω, what is the maximum power that can be delivered to the load?
2920 Cd
A light is suspended 9 m above a street and provides an illumination of 36 lux at a point directly below it. Determine the luminous intensity of the light.
1,662 lux
A light source located 2.75 m from a surface produces an illumination of 528 lux on that surface. Find the illumination if the distance is changed to 1.55 m.
3.54 m
A light source located 5m from a surface produces an illumination of 450 lux on the surface. Find the distance of the light source from the surface if the illumination is 900 lux
0.20 ohm
A load of 10 ohms was connected to a 12-volt battery. The current drawn was 1.18 amperes. What is the internal resistance of the battery?
0.0202 Ω
A moving coil instrument requires 50 mA and 100 mV for full - scale deflection. What is the value of the shunt required to convert it to read up to 5 A?
5 x 10⁻⁷ Ω*m
A nichrome wire is 1 m long and 1 x 10⁻⁶ m² in cross-sectional area. When connected to a potential difference of 2 V, a current of 4 A exists in the wire. The resistivity of this nichrome is:
8 Ω
A parallel RL circuit draws a total current of 17 A and 1.8 KW from a 120 v supply. Find R
0.50 F
A parallel RLC circuit contains a resistor R = 1 ohm and an inductor L = 2 H. Find the value of the capacitor so that the circuit is critically damped.
31.83 Hz
A parallel RLC circuit has R = 0.5 Ω, L = 10 mH and C = 2.5 mF. Determine the resonance frequency
230.7 kW
A power station supplies 60 kW to a load over 2500 ft of 000 2-conductor copper feeder the resistance of which is 0.078 Ω per 1000 ft. The bus-bar voltage is maintained constant at 600 volts. Determine the maximum power which can be transmitted.
207 kW
A process equipment contains 100 gallons of water at 25°C. It is required to bring it to boiling in 10 minutes. The heat loss is estimated to be 5%. What is the kW rating of the heater?
30
A resistance of 30 ohms and a capacitance of 132.6 microF are connected in series across a 220 v, variable frequency ac supply. At what frequency in HZ will the current be 4.4 A?
30 Hz
A resistance of 30 Ω and a capacitance f 132.6 microF are connected in series across a 220 v, variable frequency ac supply. At what frequency in Hz will the current be 4.4 A?
153 Cd
A room measuring 16 m by 8 m is to be illuminated by 8 lamps with an average illumination of 72 lm/sq. m at floor level. If 60 percent of the total light emitted is absorbed by the walls and ceiling, calculate the mean spherical candle power required for each lamp
R = 168 Ω, L = 0.455 H
A series RL circuit is connected across a 120 v, 60 Hz source and draws a current of 0.5 A at 0.70 lagging pf. Determine the values of R and L
27.8 μF
A series RLC circuit consists of 20 ohms resistance, 0.2 H inductance and an unknown capacitance. What is the value of the capacitance if the circuit has a leading angle of 45° at 60 HZ?
27.8 microF
A series RLC circuit consists of 20 ohms resistance, 0.2 H inductance and an unknown capacitance. What is the value of the capacitance if the circuit has a leading angle of 45° at 60 Hz?
18 Ω
A series circuit consists of three resistors R_1, R_2 and R_3 which are connected to a 240 v source. If the voltage drop across R_1 is 60 v when the current is 4 A and R_2 = 1.5 R_3, what is the ohmic resistance R_3?
0.625 μF
A series connected circuit has R=4Ω and L=25mH. Calculate the value of C that will produce a quality factor of 50.
224.45 kV
A short 230 kV transmission line has an impedance of 10 cis 80° Ω. The sending end power is 150 MW at 230 kV and 82% power factor. What is the voltage at the other end?
0.88 lag
A short 3 - phase transmission line with an impedance of 6 +j8 Ω per phase has sending and receiving end voltages of 120 kv and 110 kn respectively for some receiving end load at a p.f. of 0.9 lagging. Determine the sending end power factor
110,200 kW
A short three - phase line with an impedance of 6 + j8 Ω per line has sending and receiving end line voltages of 120 and 110 kV respectively for some receiving end load at a power factor of 0.9 lagging. What is the active power at the receiving end of the line?
1,212 rpm
A shunt motor with an armature resistance of 0.15 ohms is running 1,200 rpm for a load which requires an armature current of 50 A from a 230 v source. At no load, the armature current is 5 A. If the effect of armature reaction has reduced the air - gap flux 2% from no load to full load, what is the no load speed?
120m
A sine wave has a frequency of 60 Hz. Its angular frequency is
0.0124
A single - phase transformer is rated 110/440 v, 2.5 kVA. Leakage reactance measured from the low - tension side is 0.06 Ω. Determine leakage reactance on the high - tension side in per unit
2 cm
A single - phase, 10 km transmission line has 16.65 mH inductance. If the distance between the conductors is 1.0 m, what is the conductor radius?
2 cm - 0.02 m
A single-phase , 10 km transmission line has 16.65 mH total inductance. If the distance between the conductors is 1 m, what is the conductor radius?
90 turns
A single-phase transformer is rated 4,160-V primary and 250-V secondary. It has 1,500 turns in the primary and voltage regulation of 8%. What should be the number of turns in the secondary winding?
118 x 10^-9
A single-phase transmission line having a length of 15 miles is composed of two copper conductors spaced 7 ft apart having a diameter of 0.575 inch. Determine the line to line capacitance in farad if the system frequency is 60 Hz.
7.07
A sinusoidal current having peak value of 7.07 A is superimposed on dc of 5 A. If a hot - wire ammeter is used to measure the combined current in the circuit, it will indicate ____ amperes
1,182.5 rpm
A six pole induction motor is connected to a 60 Hz supply and at full - load the rotor emf makes 105 complete cycles in 2 minutes. Find the rotor speed
10.98 m
A small wind generator is designed to generate 50 kW of power at a wind velocity of 25 miles per hour. What is the approximate blade diameter?
1.2 A
A solenoid is 20 cm long and is wound with 500 turns of wire. What current will be required to set up a field strength of 3000 AT/m inside the solenoid?
25%
A squirrel cage motor is started at 50% its rated voltage. What is the starting torque relative to its rated voltage starting torque?
300
A straight conductor 100 cm long and carrying 40 A lies perpendicular to a magnetic field of 1.5 T (Wb/sq. m). What is the mechanical power in watts required to move the conductor at a uniform speed of 5 meters per second?
300 W
A straight conductor 100 cm long and carrying a current of 40 A lies perpendicular to a magnetic field of 1.5 Wb/m^2. What mechanical power in watt/s required to move the conductor at a uniform speed of 5 m/s?
360 W
A straight conductor 100 cm long and carrying a current of 40 A lies perpendicular to a magnetic field of 1.5 Wb/m². What is the mechanical power in watt/s required to move the conductor at a uniform speed of 6 m/s?
80%
A string insulator has 5 units. The voltage across the bottom most unit is 25% of the total voltage. What is the string efficiency?
83.3%
A string insulator has 6 units. The volage across the bottom most unit is 20% of the total voltage. Its string efficiency is ____
220 V
A switch is connected across a 220 V supply. What is the voltage across the switch if it is opened?
25 + j32 A
A symmetrical three-phase 240 V supplies a balanced delta connected load of 6 - j8 ohms per phase. what is the line current?
20 A
A system operates at 220 kVA and 11 kV. Using this quantities as base values, find the base current for the system.
1,728 rpm
A three - phase 4 - pole 60 Hz induction motor has a rotor resistance of 0.02 Ω/phase and standstill reactance of 0.5 Ω/phase. Calculate the speed at which the maximum torque is developed
4.83 A
A three - phase wye - delta connected, 50 MVA, 345/34.5 kV transformer is protected by differential protection. The current transformer on the high sides for differential protection is 150:5. What is the current on the secondary side of CT's?
25,653 w
A three - phase, 4 - pole, 50 Hz induction motor supplies a useful torque of 160 N - m at 4% slip. If friction and windage losses are 500 watts, determine the rotor input
0.586
A three - phase, 60 Hz, transmission line has its conductors arranged in a triangular configuration so that the two distances between conductors are 5 m and the third is 8 m. The conductors have an outside diameter of 250 mils. Find the inductive reactance in ohm per km per phase of the transmission line
0.627
A three - phase, wye - connected, 6.25 kVA, 220 volt synchronous generator has a reactance of 8.4 ohms per phase. Using the rated kVA and voltage as base values, determine the per unit reactance
51 km
A three - phase, wye connected, 20 MW load of power factor 0.866 lagging is to be supplied by a transmission line at 138 kV. It is desired that the line losses not exceed 5 percent of the load. If the per phase resistance of the line is 0.7 Ω/km, what is the maximum length if the line?
29.7%
A three-phase transformer is rated 25 MVA, 69/13.2 kV. It has a series Z = 7%. What is the new per unit impedance if the system study requires 100 MVA base and 67 kV base?
80:2.89
A three-phase transformer rated for 33 kV/6.6 kV is connected Y-Δ and the protecting current transformer on the low voltage side have a ration of the current transformer on the high voltage side
6.8%
A transformer has 4% resistance and 6% reactance drop. Find the voltage regulation at full - load 0.8 p.f. lagging
- 5 %
A transformer has negligible resistance and a p.u. reactance of 0.1. What is its voltage regulation on full load with a leading p.f. angle of 30°?
-5%
A transformer has negligible resistance and a p.u. reactance of 0.1. What is its voltage regulation on full load with a leading p.f. angle of 30°?
50
A transformer is rated 10 kVA, 440/110 V and 60 Hz when operated as a conventional 2 winding transformer. This transformer is to be used as 550/440 v step down auto transformer in a distribution system. What is the new kVA rating of the transformer in this manner?
5.66
A transmission line cable consists of 26 strands of identical copper conductors, each 1.255 mm in diameter. The length of the cable is 10 km, but because of the twist of the strands, the actual length of each conductor is increased by 5%. If the resistivity of the copper is 1.72 x 10 raised to -8 ohm/meter, what is the resistance of the cable in ohms?
10.8
A transmitter supplies 10 kW of carrier power to the antenna. The total radiated power with 40% modulation is ____ kW
0.1656 Wb
A two - pole three - phase 50 Hz star connected ac generator has 9 slots/pole and 6 conductors/slot. What is the flux per pole if the terminal voltage on open circuit is 1,100 volts. Take the coil span as unity
0.7960 A
An air core toroidal coil has 120 turns and the length is 12 cm. What is the current required to set up a flux of 1.2 x 10^-6 weber, if the cross - sectional area is 12 square cm?
7.1 MW
An ideal step-up transformer with a power factor of 1.0 is used between a 120 Vrms supply and 10 Ω resistor with the supply at the primary. The turns ratio is 70. What is most nearly the average power dissipated due to resistance R?
160 mH
An inductor supplied with 100 V AC with a frequency of 10kHz passes a current of 10 mA. What is its inductance?
134.2 lux
An office 15 m by 8 m wide is lighted by 8 lamps and each lamp has a luminous intensity of 200 cd. Allowing an absorption loss of 4,000 lm for the reflectors, walls and ceiling, calculate the average illumination on the working plane
14 KVA
An office has a total area of 500 square meters. Find the total lighting load for a unit of 28 volt - amperes per square meter
0.90 m
Approximately how far away must an isolated positive point charge of 1 x 10^(-8)C be in order for it to produce an electric potential of 100 V? The charge is in free space with e = 8.85 x 10^(-12) C^2/N*m^2.
3,000 v
Assuming a certain driving voltage causes the current to an initially discharged 1,000 microF capacitor to increase at a constant rate of 0.06 A/s, determine the voltage across the capacitor at t = 10 seconds
192 MW
At a 115 kV substation, the PT ratio is 1,000 and the CT ratio is 1200/5. The potential going into the wattmeter is 115 volts. What is the MW indicated when the wattmeter reads 800 watts?
2,091 A
At a certain point of the system network the positive, negative, and zero sequence impedance are 0.25 pu, 0.25 pu, and 0.3 pu, respectively. The base MVA is 100.The level at that point is 34.5 kV. Determine the zero sequence current for a one line to ground fault.
15.9 Hz
At what frequency will a 100 microF capacitor offer a reactance of 100 Ω?
325
CAlculate the torque in N-m developed by a 440-v dc motor having an armature resistance of 0.25 Ω and running at 750 rpm when taking a current of 60 A.
325 V
Calculate for the dc voltage when the converter consumes 1.5 kW of power at a source voltage of 230 V ac
796
Calculate the AT/m to produce a flux density of 0.001 Wb/m^2 at the center of a long straight solenoid
28.76 lb
Calculate the force that will be exerted on the scale in a pony - brake test when a 20 - HP, 1,400 rpm motor is operating at full - load. The length of the brake arm is 3 ft and the tare weight of the brake is 3.75 lb
0.25 ms
Calculate the time delay for a phase angle of 45° at a frequency of 500 Hz.
38.32%
Calculate the use factor of a power plant if the capacity factor is 35% as it operates 8,000 hours during the year
74.51 W
Compute for the core loss if the transformer consumes 75 watts when it is connected across a 240 v source and taking 1.4 A. The primary resistance is 0.25 Ω
25
Conductors supplying two or more motors shall have an ampacity equal to the sum of the following current rating of all the motors plus ___% of the highest rated motor in the group.
1.7036 r
Find the GMR in terms of the radius r of each conductor in a three bundled conductor arranged horizontally
500 kHz
Find the frequency of a radio wave whose wavelength is 600 m.
0.9063 leading
Find the power factor of the impedance 5∠-25° Ω
0.8
Find the reactive factor of the load having 30 kW and 50 kVA
344 μΩ
Find the resistance at 20°C of an annealed copper bus bar 3 m in length and 0.5 cm by 3 cm in rectangular cross section.
5 Ω
Find the total resistance id 3 Ω is connected in series with the parallel combination of 4 Ω, 5 Ω and 20 Ω
j9 pu
For a single line to ground fault, the zero sequence current is given by j3 pu. The current carried by the neutral during the fault is ____
0, 1
For an RL circuit, the power factor cannot be less than ____ or greater than ____
100%
For an existing a.c. transmission line the string efficiency is 80%. Now if d.c voltage is supplied for the same set up, the string efficiency will be:
16 μF
Four condensers of 4 μF each are connected in parallel. Their equivalent capacitance will be?
500:5
Given a 100 kVA 2,400/240 v single phase transformer. Find the current transformer (CT) ratio at the low voltage side
0.354 pu
Given a transformer of 15 MVA, 69 KV/13.8 KV with 5% impedance, find the new per unit impedance at 100 MVA, 67 KV base
0.928 pu
Given a transformer of 8 MVA, 69 KV/13.8 KV with 7% impedance, find the new per unit impedance at 100 MVA, 67 KV base
5
How many 100 kΩ will be connected in parallel to obtain 20 kΩ?
32
How many 150 - watt lamps can be supplied by a 4,800 VA branch circuit?
14
How many 240 V, 20 A branch circuits are required to supply 63,000 VA load?
13
How many 240 v, 20 A branch circuits are required to supply 60,000 va load?
240
How many commutator bars does a 6-pole dc generator with 4 coil elements per slot and 20 slots per pole has?
0.05 J
How much energy is stored by a 100 mH inductance with a current of 1 A?
20 times
How much larger is the rotor reactance of a SCIM at start - up than it is when the motor operates at 5 percent slip?
390.625
If 25 ohms and 125 amperes are the base impedance and base current, respectively for a given system, what is the base KVA?
0.737
If a certain conductor has an area of 336,400 circular mils, what is the radius of this conductor in cm?
0.737
If a certainconductorhas an area of 336,400 circular mils, what is the radius of this conductor in cm?
52.7 V
If a half - wave rectifier is used with 117 - v rms ac (house mains), the average dc output voltage is about ____
52.7 v
If a half - wave rectifier is used with 117 v rms ac (house mains), the average dc output voltage is about
49 A
If the waveform of a current has form factor 1.2 and peak factor 1.7, find the average value of the current if the maximum value of the current is 100 A
90, 75
In a transformer, the core loss is found to be 60 watts at 30 Hz and 90 watts at 40 Hz measured at the same maximum flux density. Compute the eddy current and hysteresis losses at 60 Hz in watts.
1
In dwelling units with a halfway of 3 m or more in length, at least how many receptacle outlet/s shall be installed?
120 Hz
In full - wave rectification, if the input frequency is 60 Hz, then output has a frequency of ____
150 mH
In laboratory experiment, the impedance of a coil was obtained at 60 Hz and 30 Hz. These are 75.48 ohms and 57.44 ohms, respectively. what is the inductance of the coil?
1.79 x 10^12 ft^3
Natural gas has an energy content of 0.036 watt - year/ft^3, and the coal has an average energy content of 940 watt - years/ton. If 20 percent of the net energy requirement of 2.82 x 10^5 GWHR were to be met with gas and 80 percent with coal, what amount of gas would be required?
j11.56
One conductor of a three phase line is open. The current flowing to the delta connected load through line A is 20 A. With the current in line A as reference and assuming that line C is open, what is the positive sequence current of phase C?
2 C
One hundred turns of insulated copper wire are wrapped around an iron core of cross-sectional area 0.100 m². The circuit is completed by connecting the coil to a 10-Ω resitor. As the magnetic field along the coil axis changes from 1.00 T in one direction to 1.00 T in the other direction, the total charge that flows through the resistor is:
0.6
The annual load curve is a straight line from 40 MW. What is the annual load factor?
3 times
The applied voltage in a transformer is increased by 50% and frequency is reduced by 50%. The maximum core flux density will become ____
30 microF
The capacitance between any two conductors of a three - conductor cable, with the third conductor grounded is 0.6 microF/km. Calculate the line to ground capacitance of a 25 - km length of the cable
7.98 A
The capacitance between any two conductors of a three - phase, three - conductor cable is 2 microF. The cable operates at 11 kV line voltage and 50 Hz. What is the charging current through the cable capacitance?
5.98 A
The capacitance per kilometer of a 3 - phase belted cable is 0.3 microF between the two cores with the third core connected to the lead sheath. Calculate the charging current taken by the five kilometers of this cable when connected to a 3 - phase 50 Hz, 11 kV supply
1,500 ohms
The capacitive reactance of a transmission line is 90,000 ohms per kilometer. Find the total capacitive reactance if the transmission line is 60 km long
1.25 mJ
The charge on the plates of a 1 microF capacitor is 50 microC. What is the energy stored by the capacitor?
35.5 mH
The conductors of a three - phase transmission line are arranged in the form of an equilateral triangle with sides of 6 m each. If the conductors are 500 mils in diameter and the line is 25 km long, what is its inductance per phase?
93.38%
The core loss of a 5 kVA single - phase transformer with normal voltage applied to the primary is 75 watts. The maximum efficiency occurs at 60% of full - load kVA. What is the full - load efficiency of the transformer at 0.80 power factor?
137.8 mJ
The current in an inductor is given by i = 5 + 16t amperes. The self-induced emf in it is 10 mv. Find the energy stored in the inductor at t = 1 second.
0.25 H
The current in the coil of a large electromagnetic falls from 6 A to 2 A in 10 ms. The induced emf across the coil is 100 v. What is the self - inductance of the coil?
16,343 W
The dc armature winding resistance between terminals of a 750 kVA, 4400 volt, three-phase alternator is 0.9 ohm. Calculate the copper loss in the winding at full-load.
19.2 v
The field system of a 50 Hz alternator has a sinusoidal flux per pole of 0.1 Wb. Calculate the emf generated in one turn which spans two-thirds of a pole pitch.
120°
The field system of a 50 Hz alternator has a sinusoidal flux per pole of 0.1 Wb. The emf generated in one turn of coil is 19.2 v. What is the span of the coil?
159.2 x 10^3 AT/m
The flux produced in the air gap between two electromagnetic pole faces is 6 x 10^-2 Wb. Length of air gap is 1.4 cm and cross - sectional area of the gap is 0.3 m^2. Find the magnetic field intensity
1,740 rpm
The frequency of the emf in the stator of a 4 - pole induction motor is 60 Hz, and that in the rotor is 2 Hz. At what speed is the motor running?
20
The growth rate of the energy consumption in our country is 6.9%. In how many years will the energy be quadrupled?
289 cd
The illumination of a surface 3.40 m directly below a light source is 25 lux. Find the intensity of the light source?
80
The illumination on a surface is 100 lm/m^2. The reflection coefficient of the surface is 80%. What is the maximum brightness of the surface in Cd/m^2?
0.337
The input power to a 3 - phase induction motor running without load is measured by two wattmeter method. One wattmeter indicates -220 watts and the other one indicates 940 watts. What is the no - load power factor of the motor?
24
The lighting load for a dwelling expressed in terms of a unit load in volt - ampere per square meter must be at least ____
20
The output current corresponding to maximum efficiency for a transformer having core loss of 100 watts and equivalent resistance referred to secondary of 0.25 Ω is ____ amperes
85
The overload KVA of each transformer of an open-delta bank is 11.55. if each transformer is rated 37.5 kVA, then what is the kVA of the balanced 3ϕ load?
1.2083 cm
The per phase line loss in a 40 km long transmission line is NOT to exceed 60 kW while it is delivering 100 A per phase. If the resistivity of the conductor materials is 1.72 x 10-8 ohm-meter, determine the required conductor diameter.
0.60
The per unit impedance of a circuit element is 0.30. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be
7 pu
The per unit reactances of a synchronous generator are X_d = 1.1, X_d' = 0.24, X_d" = 0.15. The generator is operating without load at 5 percent above rated voltage when a three - phase short circuit occurs at its terminals. What is the per unit subtransient fault current?
2 pu
The per unit value of a 2 ohm resistor at 100 MVA base and 10 KV base voltage is ____
1,458 A
The positive, negative and zero sequence reactances of a 20 MVA, 13.2 KV synchronous generator are 0.3 pu, 0.2, and 0.1 pu, respectively. The generator is solidly grounded and is not loaded. A line to ground fault occurs on phase a. Neglecting all the resistances, determine the positive sequence of the fault current
550 J
The potential difference between two conductors is 110 v. How much work is done in moving a 5 coulomb charge from one conductor to the other?
10
The power delivered to a loud speaker of an amplifier is 30 dB above 10 mW. It is equivalent to ___ watt.
0.628
The power factor of a 20 MW, 13.2 KV, 3 - phase motor is corrected to 0.9 by connecting a 230 microF capacitor. What is its initial power factor?
108 MW
The power plant has a peak demand of 90 MW, capacity factor of 0.50, use factorof 0.80 and load factor of 0.60. Find the plant installed capacity.
40 w
The power required to produced a gain of 10 dB over 4 w of original power is ____
P/9
The primary of a 3 : 1 step-up transformer is connected to a source and the secondary is connected to a resistor R. The power dissipated by R in this situation is P. If R is connected directly to the source it will dissipate a power of:
4.40 mWb
The primary of transformer has 200 turns and is excited by a 240 V, 60 Hz source. What is the maximum value of the core flux?
4.4 mWb
The primary of transformer has 200 turns and is excited by a 240 v, 60 Hz source. What is the maximum value of the core flux?
29.33 Ω
The resistance of a winding wire made up of copper is 25 ohms at 30°C. What is its resistance when it operates at a temperature of 75°C? Assume temperature coefficient at 20°C = 0.004.
20
The rotor emf of a 440 v, 4 pole, 60 hz, 3 phase induction motor makes 108 complete cycles/minute when the shaft torque is 81.6 N-m. Find the output hp of the motor
1710 rpm
The rotor of a 3-phase, 60 Hz, 4-pole inductor motor takes 120 kW at 3 Hz. What is the rotor speed of the induction motor?
0.0346 sec
The shunt winding of a machine has a resistance of 80 Ω and an inductance of 4 H is suddenly switched on to a 220 volt supply. Find the time taken for the current to rise to half its steady state value?
300
The starting current of a 15 hp, 460 V, 3-phase induction motor is 130 A. What voltage in volts should be applied to the motor so that the starting current will not exceed 84.8 A?
500 mA
The voltage across a 50 microF capacitor rises at a constant rate of 10 v/ms. Calculate the current through the capacitor
75
The voltage applied across the resistor was reduced by 50%. The power consumed by the resistor will be reduced by ____%
1:5
Three 1Φ transformers are bank in Δ/Y to supply a 3Φ load from a 400v, 3Φ source. The line voltage on the load side is 3,464 volts. What is the ratio of transformation of each transformer>
2.540 V
Three 30.1 step - down transformers are connected wye - delta for stepping down the 132,000 - volt three - phase transmission voltage. Calculate the secondary line voltage
2,540 V
Three 30:1 step down transformers are connected wye - delta for stepping down the 132,000 volt three phase transmission voltage. Calculate the secondary line voltage
500 w
Three 40 Ω non - inductive resistances are connected in ye across 200 v, 3 - phase lines. If one of the resistors is disconnected, what would be the power taken from the mains?
20 Ω
Three 6.66 Ω resistors are connected wye. What is the equivalent of each delta connected resistors?
18.26 v
Three capacitances C_1 = 6 microF, C_2 = 7 microF and C_3 = 18 microF are connected in series across a 120 v supply. Find the voltage across C_3
178 microC
Three capacitances of 4 microF, 6 microF and 5 microF are connected in series across a 110 - volt dc source. Find the charge passing through each capacitor
33.3
Three capacitors are connected in series across a 135 v supply. The voltage across them are 30, 45 and 60 v and charge on each is 4,500 microC. Find the total capacitance in microfarads
12 - j21
Three equal impedances Za = Zb = Zc = 4-j7 ohms are connected in wye. Find the equivalent impedance in ohm if these impedances are connected in delta.
73.3
Three identical resistors are connected in wye across 220 v, 3 - phase lines. The line current is 12.7 A. To what value in volts should the line voltage be changed to obtain the same line current with the resistors connected in delta?
112 - j51 v
Three impedances Z_1 = 2.2 + j2.2 Ω, Z_2 = 10 + j10 Ω and Z_3 = -j5 Ω are connected in series. The voltage across Z_1 is 26.59 - j4.69 v. What is the total voltage?
18,392 W
Three impedances Z_ab = 4- j3 ohms, Z_bc = 3 + j4 ohms, Z_ca = 10 + j0 ohms are connected in delta across a 220 volts, three phase balanced source. What is the total power of the circuit?
24 Ω
Three resistances of 4, 9, and 11 ohms are connected in series and then in parallel. Find the effective resistance for series connection.
110
Three resistors A, B, C are connected in series to a 120-v supply. If the resistor A=50 ohms and the voltage across resistor B=40 V when the current is 1/2 A. What is the resistance of resistor C in ohms?
100
Three resistors A, B, and C are connected in series to a 120-v supply. If the resistor A=60 ohms and the voltage across resistors B=40 v when the current is 1/2 A, what is the resistance of resistor C in ohms?
4.62 Ω
Three resistors of 10 Ω, 15 Ω and 20 Ω are connected in parallel. What is the total resistance?
43.3
Three single-phase transformers rated 25 kVA each are connected in delta-delta to supply a balanced load of 75 kVA. One transformer is removed for repair, what is the kVA of each remaining transformer?
60.51 v
Three sinusoidal generators and a battery are connected in series with a coil whose resistance and inductance are 8 Ω and 26.53 mH, respectively. The frequency and rms voltage of the respective generators are 20 Hz, 15 v, 60 Hz, 30 v and 80 Hz, 50 v. The battery voltage is 6 v. Determine the circuit rms voltage
6,928 V
Three units of 1:10 transformers are connected in delta/wye to supply a 3 - phase load from a 400 v, 3 - phase source. What is the line voltage on the load side?
200 V
To a series RLC circuit, a voltage of 10 V is applied. If Q of the coil at resonant frequency is 20, the voltage across the inductor at resonant frequency will be
150 KW
Twenty tons of water are heated in 12 hours. If water is to be heated from 25°C to 95°C, find the KW rating of the heater if its efficiency is 92%.
92.4%
Two (2), 1Φ, 25-KVA transformers are connected in V-V bank supplying a balanced 3Φ load of 40 kVA. What is the percentage load of the bank/
220 w
Two 100 watt lamps connected in series across a 220 v line draw 1 A. What is the total power consumed?
220 W
Two 500 watt lamps connected in a series across a 220 volt line draw 1 A. What is the total power consumed?
0.813 lagging
Two alternators are operating in parallel supplying a common load of 425 kW at 0.85 power factor lagging. Alternator A contributes 60 kVAR at 0.92 power factor lagging. Solve for the power factor of alternator B.
18.75
Two capacitors C_1 = 50 microF and C_2 = 30 microF are connected in series. Find the equivalent capacitance in microF
4 pF
Two capacitors in series are charged across a 24 v source. If C_1 is 12 picofarads and the voltage across it is 6 v, find C_2
5.5 kg
Two charges of 2 x 10^-5 C and 3 x 10 ^-6 C are placed 10 cm apart. Find the force in kg on each charge
6 H
Two coils have self-inductance of 5H and 1H, the mutual inductance being zero. If the two coils are in series, what is the total inductance will be?
31 mH
Two coils having inductances of 20 mH and 50 mH are wound on top of each other. Calculate the mutual inductance between the two coils if the coupling coefficient k = 0.98
0.0075 N/m
Two conductors carrying 50 amperes and 75 amperes respectively are placed 10 cm apart. Calculate the force between them per meter
2
Two coupled coils have self - inductances L_1 = 2 H and L_2 = 0.5 H, and a coefficient of coupling k = 0.9. Determine the turns N_1/N_2 of the two coils
100 sin 400t
Two coupled coils have self - inductances L_1 = 50 mH and L_2 = 200 mH and a coefficient of coupling K = 0.50. If i_1 = 5 sin 400t A, find the voltage at coil 2
3.4 x 10^-7 m
Two electrons in a vacuum experience a force of 2 x 10^-15 N. How far apart are the electrons?
2.7 nC
Two equal charges of opposite signs are separated by a horizontal distance of 70 mm. If the resultant electric field at the midpoint of the line is 4 x 10⁴ N/C. What is the magnitude of each charge?
3,556 kW, 4,444 kW
Two exactly similar turbo - alternators are rated 5 MW each. They are running in parallel. The speed load characteristics of the driving turbines are such that the frequency of alternator one drops uniformly from machines share a load of 8,000 kW?
8.33
Two generators G₁ and G₂ are rated 15 MVA, Z equals 0.10, 11 kV and 10 MVA, Z equals 0.10, 11 kV, respectively. The generators are connected to a transformer of 15 MVA, 11 per 66 kV and 6 percent impedance. Calculate the fault current in per unit when three-phase fault occurs on the high voltage side of the transformer.
2C/3
Two identical capacitors, each with capacitance C, are connected in parallel and the combination is connected in series to a third identical capacitor. The equivalent capacitance of this arrangement is:
5.625 mH
Two identical coupled coils have an equivalent inductance of 40 mH when connected in series aiding and 17.5 mH in series opposing. What is the value of the mutual inductance?
0.39
Two identical coupled coils have an equivalent inductance of 80 mH when connected in series aiding and 35 mH in series opposing. Find the coefficient of coupling.
0.391
Two identical coupled coils have an equivalent inductance of 80 mH when connected in series aiding and 35 mH in series opposing. What is the value of the coefficient of coupling K?
0.0572 lux
Two lamps having luminous intensity of 250 and 300 candelas, respectively are placed 100 m apart. Lamp A is placed 10 m above the ground while lamp B is placed 20 m above of the same level. What is the illumination at the center of the lamp posts at ground level?
4.0 x 10⁻⁴
Two long straight wires are parallel and carry current in the same direction. The currents are 8.0 and 12 A and the wires are separated by 0.40 cm. The magnetic field in tesla at a point midway between the wires is:
271
Two million cubic meters of water is stored in a reservoir feeding a water turbine. If the center of mass of the water is 50 m above the turbine and losses are negligible, how much power in MWHR per second will that volume of water produce? The density of water is 993 kg/m^3
2I
Two resistors R_1 and R_2 are connected in parallel. R_1 is twice of R_2. If the current in R_1 is I, what is the current in R_2?
63,000 N
Two similar poles, each of 1 Wb, placed 1 m apart in ar will experience a repulsive force of
40
Two single phase transformers each rated 75 kVA are connected in V or open-delta to serve a three-phase load of 120 kW at 0.80 power factor lagging. To prevent the overloading of transformers, determine the size of the capacitor in kVAR.
F/4
Two small charged objects attract each other with a force F when separated by a distance d. Ifthe charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes:
193.2 kW, 51.8 kW
Two transformers are connected in open delta and deliver a balanced three - phase load of 245 kW at 460 volts and a power factor of 0.707. Calculate the power delivered by the individual transformers
0.891
Two wattmeters connected to measure power read W1 = 30 kW and W2 = 55 kW. What is the power factor?
69.1 ∠ 0°
Two-wattmeters both have readings of 5 kW when connected for the two-wattmeter method in a 480-v three-phase circuit that has a balanced Δ load. Find the Δ phase impedance.
50.7 microF
What capacitance must be placed in series with an inductance of 0.05 henry, so that when the frequency is 100 Hz, the impedance becomes equal to the ohmic resistance?
2.0 millicoulomb
What charge would be taken by a practical to 10 micro farad capacitor if connected to a 200 volt supply?
20 A
What is the branch circuit ampacity of a hermetic motor with a full - load current of 16 A?
6.25 x 10^-9 F/km
What is the capacitance per kilometer of two parallel wires 7 mm in diameter placed 30 cm apart from each other in air
6.25 x 10⁻⁹ F/km
What is the capacitance per kilometer of two parallel wires 7 mm in diameter placed 30 cm apart from each others in air?
51
What is the device function number for overcurrent relay?
0 v
What is the emf induced across an inductor with 150 mH inductance and constant current of 4 amperes?
0 v
What is the emf induced in a coil of 500 turns and with a constant flux of 10^8 maxwells?
3n(n + 1) + 1
What is the empirical formula to calculate the number of strands?
23.0 μF
What is the equivalent capacitance for capacitors of 4, 7, and 12 μF connected in parallel?
2.79 KHz
What is the frequency where the reactances of 57 microH inductor and a 57 microF capacitor are equal?
3.75 mWb
What is the maximum flux in mWb of a transformer with 200 primary turns when connected to a 60 Hz, 200 v supply?
144 W
What is the maximum power that can be drawn from a 12-V battery that has an internal resistance of 0.25 Ω?
3600 rpm
What is the maximum speed at which a 60 Hz synchronous machine can be operated?
25 A
What is the minimum ampacity of branch circuit conductor for a hermetic motor whose full - load current is 20 A?
16.25
What is the minimum required ampacity of the feeder conductors supplying a 5 A, single - phase motor and a 10 A lighting load?
576 J
What is the potential energy stored in the electric field of a 200-μF capacitor when it is charged to a voltage of 2400 V?
16 sin² (3t)
What is the power given v = 4 sin 3t and i = 4 sin 3t?
2
What is the quality factor Q of an RLC series circuit having R = 5Ω, L = 10mH, and C = 100 μF?
2.74 Ω
What is the resistance of 2,000 m of copper wire that has a resistivity of 1.72 x 10^-8 Ω-m and a diameter of 4 mm?
2.75 Hz
What is the rotor frequency of an induction motor if the rotor speed is 1,145 rpm?
591,300
What is the total energy generated by a station in kWHR in a year if its maximum demand and annual load factor is 150-kW and 45% respectively?
1,885 lm
What is the total flux of light emitted from a source having a uniform intensity of 150 candlepower?
4.5 kW
What is the total power consumed by the load when the readings of two wattmeters are 5 k and -0.5 kW?
3 kΩ
What is the total resistance of eleven 33 kΩ resistors connected in parallel?
0.1 H
What is the value of inductance of a coil that induces 100 volts when the current changes at the rate of 2 mA in 2 microseconds?
-11 var
When 3 A flows through a circuit with an input admittance of 0.4 + j0.5 S, what reactive power doe the circuit consumed?
73.2
When a V - V system is converted into a delta - delta system, increase in the capacity of the system is ____ percent
100 A
When a line to ground fault occurs, the current in a faulted phase is 300 A. What is the zero sequence current in this case?
1,800 mm
When installing two grounding electrodes, the minimum distance between them is ____
6 Ω and 3 Ω
When two resistors R_1 and R_2 are connected in parallel across a battery, they consume a total of 50 W and draw a total current of 5 A. When the two resistors are then connected in series across the same battery, they consume a total of 225 W with the same total current of 5 A. Determine R_1 and R_2
58%
Wye - delta starting is equivalent to autotransformer starting with ____ tapping