OES-4015- TEST 2 - Multiple Choice/ Fill in Blank/ True-False.
store, electrostatic
Capacitance is the property of a circuit, or circuit component that allows it to ______ electrical energy in _________ charge form.
farad
The standard unit of measurement for capacitance is the ________.
capacitor
Two wires of a circuit are separated by air, they will act as a _______________.
1
Where in the picture is line voltage measured?
4
Where in the picture is phase current measured?
1
Where in the picture is phase voltage measured?
3
Where in the picture is phase voltage measured?
receiving, storing
Where voltage and current are both +ve or both -ve (+ve power), the capacitor is ________ and ________ electrostatic energy.
Clockwise
ABC sequence is the result of __________ phase rotation
Counter Clock Wise
ACB sequence is the result of __________ phase rotation
counterclockwise
According to convention, vectors are rotated ______________________.
requiring, consuming
Coils can be viewed as __________ or ___________ magnetizing VARs
b)false leading
If XC is greater than XL, the circuit has a lagging power factor. a)true b)false
henry
The unit of inductance is the _________.
inversely proportional
The value of XC in ohms is _______________ to the capacitance in farads and the frequency of the impressed ac voltage.
a)
The voltage (V) across an inductor (L) leads the current. a)true b)false
Line, Line
Voltages across the line wires is called the _______ to _______ voltage
phase
Current in a pure resistor is in ___________ with the voltage
F
The delta connection is the most common three phase configuration T or F
a)
The power factor is the ratio of the power loss to the volt-ampere rating when the capacitor is operated at the rated voltage and frequency. a)true b)false
a)
The power in a capacitor, in watts, at any instant is equal to the product of the voltage and current values at the same instant. a)true b)false
magnetic field, proportional
The induced voltage of a conductor, coil, or circuit is caused by a changing _____________ cutting across the circuit components. This voltage is ____________ to the rate of change of the lines of force.
Current, current
The line _________ and phase _________ are the same because the wye configuration is in series.
a)
The opposition voltage that develops as the capacitor charges is really a counter voltage because it opposes the line voltage and limits the current. a)true b)false
Sequence/Rotation
The phase __________ is the order in which the three voltages follow each other
Equal
The phase and line voltages have common points; thus, these voltages are _________.
capacitive reactance
Also any increase in the frequency or the capacitance results in a decrease of the _________ _________ (ohms
leads, 90
Current in a circuit with pure capacitive reactance ______ the impressed voltage by ______ electrical degrees.
b) In a circuit containing inductance, current will increase at a much *slower* rate toward a maximum value than it does in a circuit containing resistance only.
In a circuit containing inductance, current will increase at a much faster rate toward a maximum value than it does in a circuit containing resistance only. a)true b)false
current
In a inductor, there can't be any instantaneous ______ changes.
150%
Three Phase generators have a capacity of _____% that of a single phase unit
10E-6 farad
What is a Microfarad?
10E-12 farad
What is a Picofarad?
releasing
When power is -ve, then the capacitor is _________ energy
store
A capacitor can ________ electrical energy.
charges, discharges
A capacitor connected to an AC power supply repeatedly _________ and _________ as the AC voltage changes polarity.
2
Where in the picture is line current measured?
vector
A _____________ is any quantity having both magnitude and direction.
b) resistance
A circuit is in resonance when the circuit is viewed from the input terminals and it appears to be pure impedence. a)true b)false
frequency, capacitance
An increase in either the _____________ or the ____________ gives rise to an increase in current for a given applied voltage in a RC circuit.
zero
At the resonant frequency, the phase angle between the current and the line voltage is ___________.
sources
Capacitors can be viewed as __________ of magnetizing VARs
Reverse
Interchanging the connections of any two line wires will _____________ the direction of rotation and change the phase sequence.
capacitive reactance
The current-limiting effect of capacitance in an AC circuit is called __________ __________ and is measured in ohms
capacitive reactance
The current-limiting effect of this countervoltage (capacitance) in an ac circuit is expressed in a unit called __________________ and is measured in ohms
resonance
When the inductive reactance in a circuit is equal to the capacitive reactance in a coil, the circuit is said to be in _____________.
phase
When the inductive reactance in a circuit is in resonance, current and voltage are in _________.
Inductance
__________ is the ability of a circuit component, such as a reactor coil, to store energy in the electromagnetic field.
c) JAAAA WEITER SOOOO!
In a pure inductive circuit, the current lags the voltage by ____°. a)45 b)180 c)90 d)260
stationary armature (stator), 120
A simple three phase generator consists of three coils or phase windings placed in the slots of a _____________. The windings are placed so that the three induced voltages are ___ degrees apart.
b) *Increasing* the frequency of an ac inductive series circuit decreases the circuit current.
Decreasing the frequency of an ac inductive series circuit decreases the circuit current. a)true b)false
lagging
If XL is greater than XC, the circuit has a __________ power factor.
T
If the currents and voltages in a delta system are severely unbalanced, the three-phase power factor has no real significance. T or F
a)
Impedance is the result of the combination of resistance and reactance. a)true b)false
leads, 90
In Capacitance, the current ______ the voltage by ____ degrees
lags, 90
In Inductance, the current ______ the voltage by _____ degrees
voltage
In a capacitor, there can't be any instantaneous ______ changes.
a)
In a circuit containing both resistance and inductive reactance, the angle of lag is less than 90° and is equal to the vectorial sum of both the XL and R components. a)true b)false
b) In a dc circuit, the inductive effect *stops* once the current reaches the value defined by Ohm's law and remains constant.
In a dc circuit, the inductive effect Starts once the current reaches the value defined by Ohm's law and remains constant. a)True b)False
F
In a wye connection, If the voltage in each phase winding is 120v, then the line voltage is 240V across each of the line connections T or F
a)
In an RLC circuit, When in resonance, the inductive reactance equals the capacitive reactance. a)true b)false
b) In an *ac* circuit with the same effective voltage as an equivalent *dc* circuit, the circuit current will be less than in the *dc* circuit because of the choking effect of inductance in the ac circuit.
In an dc circuit with the same effective voltage as an equivalent ac circuit, the circuit current will be less than in the ac circuit because of the choking effect of inductance in the dc circuit. a)true b)false
Phase
Induced voltage in each winding of a 3-phase circuit is called _________ voltage
b) Inductance and capacitance have *opposite* effects in an ac circuit.
Inductance and capacitance have same effects in an ac circuit. a)true b)false
ohms
Inductance in an AC circuit also causes a counter voltage. The current-limiting effect of this counter voltage is measured as _________ of inductive reactance.
b) Inductance in an *ac* circuit is just as effective in limiting current as resistance.
Inductance in an dc circuit is just as effective in limiting current as resistance. a)true b)false
electrical inertia
Induction in an electrical circuit can be called ___________.
c & d
Kirchoff's current law states: a) the sum of all voltages at a series junction point is always zero b)the sum of the voltages leaving a point must equal the sum of the currents entering that point c) the sum of the currents at a junction point in a circuit network is always at zero d)the sum of the currents leaving a point must equal the sum of the currents entering that point
T
Many wye-connected systems have a neutral wire in addition to the three line wires. This neutral wire is connected between the common point of the coils in the alternator and the common point of the wye-connected load. Such a system is called a three-phase, four-wire, wye-connected circuit. T or F
wye
The ______ connection can be easily identified by the fact that it is made by connecting one end of each phase together at a common point.
dielectric
The ___________(insulator) of the capacitor prevents electrons from being conducted through the capacitor
delta
The ______connection is made by connecting the finish end of one phase to the start end of another.
direction
The charging current also alternates in _________ as the capacitor charges and discharges
a)
The current (I) in a capacitor (C) leads the voltage (V). a)true b)false
a)
The induced voltage or counterelectromagnetic voltage in a series inductive circuit opposes the impressed voltage and thus limits the circuit current. a)true b)false
a)
The length of time required for the current to decay to zero, once the circuit is de-energized, equals the time required for the current to rise to its Ohm's law value when the inductive circuit is energized. a)true b)false
T
The power, in watts, taken by a three-phase, three-wire system can be measured with two wattmeters. This method can be used to measure the power in both a three-wire wye system and a three-wire delta system. T or F
F because it looks like a greek letter, voltage is constant in a delta.
The term delta is used because the schematic diagram of this connection results in a drastic change (or delta) in voltage. T or F
a)
The three phase circuit consists of a) three single phase circuits combined b) a circuit with a resistor, capacitor and inductor c) A circuit with a resistor and inductor d) non of the above
Wye (star), Delta
Three Phase generators/motors transformers can be connected in the _______ or ________ configurations
F
Three phase power is pulsing much like single phase T or F
F cheaper initial costs as well.
Three phase systems are higher in initial cost but lower in maintenance T or F
a)
Three phase systems can operate a) single phase systems b) double phase systems c) only other three phase systems d) non of the above
T
Three phase units offer a savings of 25% copper over singles phase units. T or F
wye (star), delta
Three-phase connections can be divided into two main types, these are _____ and _____
120
Three-phase power is produced by placing three separate windings spaced ____° from each other.
5
Where in the picture is line current measured?
capacitive reactance
Xc is _________________________
c)
_________ Law states that in all cases of electromagnetic induction, the induced voltage and the resultant current are in a direction that opposes the effect that produces them. a)Ohms b)Henry c)Lenz d)Adolfs
Inductive reactance
______________ is the opposition in an ac circuit due to inductance.
3,4,6
Where in the picture is line voltage measured?
2
Where in the picture is phase current measured?
a) GOOD JOB ! KEEP GOING!
A capacitor should be used only for the type of service for which it is designed. a)true b)false
b) A circuit or circuit component is said to have an inductance of one henry when a current change of one ampere per second induces a voltage of one *volt*
A circuit or circuit component is said to have an inductance of one henry when a current change of one ampere per second induces a voltage of one milli volt. a)true b)false
a) WENN DU DAS FALSCH GEMACHT HAST, SPRING VON DER BRUECKE!!!
The conservation of energy principle states that the total power supplied to a circuit is equal to the sum of the values of power consumed in each of the individual circuit components. a)true b)false
Ohm's Law.
The current, in amperes, in an AC circuit containing capacitance is determined using a form of_____ ______.
counter
The opposition voltage that develops with a capacitor in a AC circuit is really a ________ voltage.
lags, 90
Current in a pure inductive reactance _____ the impressed voltage by ___ electrical degrees.
decreases
As the charge increases in a capacitor, current _________
Vpeak since that will be the maximum voltage that will ever be supplied to the capacitor.
Capacitors that are used in either AC circuits have a rating known as their DC working voltage. That is the rating of _______.
