Missed NETA 2 Questions
The interrupting rating of Class J fuse is _____ amperes.
200,000
A disconnecting means should be provided for all ungrounded conductors derived from stationary battery system over ____ volts.
60
How many 0.5 V, 0.2 A cells are required to create a 12 V battery that has a 0.5 A capability?
72
A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
8.66:1
Temporary safety grounds:
Are sized with consideration of available short circuit current and time duration.
Which of the following would be describe a 59 device?
Overvoltage
ASTM test method D924 measures which of the following?
Percent
What effect does sustained voltage above the voltage where PD begins have on XLPE cable?
Possible Further Deterioration
Which of the following is covered by NFPA 70E?
Power company warehouse
Inductive Reactance of a coil is determined by?
XL = (2πfL)
How many connection points would you expect to find on a Kelvin Bridge?
4
What is the reactance of a 15 µF capacitor when the applied frequency is 2.5 kHz?
4.24 ohms Xc = 1/(2πfC)
What is the restricted approach Boundary for a 50V system?
Avoid contact
Correcting the power factor of three-phase loads normally involves adding:
Capacitance in parallel
What is the function of a circuit breaker?
Change current flow
Medium-voltage motor starters use blowout coils. What do these do?
Creates a magnetic field that helps draw the arc into the arch chute
Inductors resist sudden changes in _______?
Current
Schematic diagrams are principally utilized to show:
Device/circuit operation
The unit circular mil is equal to the _________?
Diameter of the wire in mils squared.
What is indicated when the turns ratio test set is hard to crank and the correct exciting voltage cannot be reached?
Incorrect polarity or Shorted specimen windings
A medium voltage cable might have PVC:
Jacket
Which of the following hard hats would you choose to protect from blows to both the top and sides of the head?
Type 2
What is the recommended maximum acceptance test voltage for a DC overpotential test on a 35 kV cable with 133% insulation level?
124 kV
What is the reactance of a 25 µF capacitor when the applied frequency is 400 Hz?
15.92 ohms
NFPA 70E Article 110.2 lists several training requirements for employees exposed to hazards, which of the following is not included?
Heavy equipment
An ampere is best defined as:
One coulomb per second.
How would you verify the long-time pickup of a type OD-series or EC-series trip device?
Raise current slowly until trip arms begins to move
Conductive lube must be applied to circuit breaker stabs to keep__________ at a minimum in the circuit path.
Resistance
For which reason does a kelvin bridge have 4 leads?
To eliminate extra impedance
A wye-delta transformer has a turns ratio of 2:1. It has a secondary line voltage of 480 V. The secondary is connected to a wye-connected three-phase resistive load of 50 ohms in each phase. How much is the primary line current?
2.77 A
Which device functions when the circuit admittance, impedance or reactance increases or decreases beyond predetermined limits?
21
A 5 H inductor is subjected to an electric current that changes at a rate of 4.5 amps per second. How much voltage will be dropped by the inductor?
22.50
A wire that has a diameter of 162mls has an area of ______ circular mils?
26,244 (circular mil=A=d^2)
Class 4 rubber insulating gloves are proof tested at 40,000 VAC, what is the AC max use voltage of these gloves?
36,000
A capacitor has a capacitance of 100 microfarads on a 120V 60Hz line, how much current flows through the capacitor?
4.52 A
What size cable would you expect to find on ASTM Grade 5 personal protective grounds?
4/0 AWG
The basic requirements for switchgear and switchboards are covered in NFPA 70 article ________.
408
At what voltage level would you VLF test newly installed cable rated 35kV Phase-to-Phase, according to NETA standards?
44kV
If 230 volts is applied to a 160 turn primary winding, what is the voltage in the 320 secondary winding of the transformer?
460
A wye-delta transformer has a turns ratio of 2:1. It has a secondary line voltage of 480 V. The secondary is connected to a wye-connected three-phase resistive load of 50 ohms in each phase. How much current flow is there in each load resistor?
5.54 A
Insulation resistance testing on a 480V motor is usually conducted at which voltage for acceptance?
500 VDC
How much torque is required to produce 300 HP at 2700 RPM?
584 lb-ft torque = HP x 5252 / RPM
AC dielectric withstand acceptance test voltage of a 15kV delta-wye 500kVA dry-type transformer should not exceed _____ percent of factory test voltage for one minute duration.
75
What is the expected contact-resistance measurement for a 4000A 480V air circuit breaker in good condition?
8-24 microhms
A vertical run of 4/0 AWG copper shall be supported at intervals not exceeding ____.
80 ft
The ICEA and AEIC recommend an acceptance testing voltage level for shielded cables at ___ of the final factory DC test voltage.
80%
First aid, emergency response, and resuscitation (CPR) training for employees shall occur ___________.
At a frequency that satisfies the requirements of the certifying body
A given voltmeter has an accuracy of 7.5% and can read 150V at full scale, what could be said for such meter?
At full scale the meter could be off by 7.5% and 15% at half scale.
Place the hierarchy of backup power systems to the order in which they appear in the NEC. a. Legally required standby systems b. Emergency power systems c. Optional standby systems
B, A, C
Resistance grounding is used for voltages:
Between 3.3 kV and 11 kV
Buchholz relays are installed:
Between main tank and conservator
Which of the following loads or devices may be protected from damage due to over long low voltage conditions by an undervoltage relay?
Motors
The average time it takes for circuit breaker contacts to move from contact part to 75% of the full open gap is defined as:
Opening speed
Ground Fault Protection Systems are primarily provided for which of the following?
Solidly grounded systems
An electrolyte can be checked to ensure that it has correct chemical composition by measuring it's:
Specific gravity
Which type of potential might you encounter while walking next to a structure when a fault to ground occurs?
Step
In motors, which of the following relay protection is provided as protection for unbalance in the loading of the machine?
Thermal protection
For providing short circuit protection, a fuse rated in continuous amperes shall not exceed _____ times the ampacity of the conductor.
Three
If a single three-phase transformer of the proper ratings is not available, three single-phase transformers can be connected to do the job. When this is done, the connection is called a?
Three-phase bank
What is an application for a circuit switcher with a pre-insertion inductor?
Transient control for capacitor bank switching
Electrical system wiring and equipment supplied from storage batteries are subject to the National Electric code. (T/F?)
True
Types NM, NMC, and SE cables can be used for feeder temporary installments without height limitation and without concealment. (T/F?)
True
The primary protection element used for internal transformer faults is ________?
Differential
Which of the following would best describe a 87 device?
Differential
Class C hard hats are a good choice for protection from electrical hazards. (T/F?)
False
De-energizing the load side of a switchboard by operating the disconnecting means will de-energize the ungrounded service conductors. (T/F?)
False
Even though operating and time characteristics vary between different fuse types and constructions, fuses are intended to operate at their ampere rating. (T/F?)
False
Fiber optic cables are desirable because they have a low resistance to electromagnetic noise. (T/F?)
False
In an inductive circuit, the voltage waveform lags behind the current waveform. (T/F?)
False
High voltage circuit breakers are __________ devices?
electromechanically operated
In a capacitor, the current _________ the applied voltage by ________.
leads, 90 degrees
In an electrical transformer, 10% rise in temperature will reduce the life of the insulation by _________.
1/2
If a current of 30 amps is measured with a 100 amp 3% ammeter, the maximum possible error in terms of actual error is?
10%
Reclosers have the same, more, or less interrupting capabilities as sectionalizers?
More
A given 1000kVA wye-wye transformer has a secondary rated voltage of 480/277V, what is the line current of this transformer?
1203A
What is the reactance of a 25µF capacitor when the applied frequency is 400Hz?
15.92 ohms XC = 1 / (2πfC)
Three 1000kVA single phase transformers were connected to form a closed delta connection. If one of these transformers was removed and the remaining configured as a open delta. What is the output capacity of this new configuration?
1740 kVA
What is the approximate specific gravity of Silicone insulating fluid?
0.98
What is the minimum acceptable temperature corrected insulation resistance value for a 480V emergency generator manufactured in 1965?
1.5 Megohms
When performing an instantaneous pickup test on a molded-case circuit breaker with a non-adjustable trip, what is the pickup tolerance?
+/- 25%
Electro-magnetic relays may be operated by?
-Electro-magnetic attraction -Electro-magnetic induction -Thermal effect
The lowest equipment temperature acceptable for power factor testing on high-voltage bushings is:
0 C
How much energy does a 2.5MW turbine produce in one complete cycle?
0.012 KWh
Calculate the circuit time constant of an inductor having resistance value of 100 ohms and an inductance value of 4 Henry:
0.04 sec T = L/R
According to NETA acceptance testing specifications what is the maximum acceptance power factor at 25 degrees Celsius for new mineral oil to be used in new equipment rated 69KV and below?
0.05%
A parallel circuit composed of a 150 ohm and 270 ohm resistor has a supply voltage of 120 V. What is the current in the 150 ohm resistor?
0.8 A I = V/R
Applying a solidly grounded wire immediately after performing a high-potential test:
May damage the insulation under test
Automatic transfer switches on legally required standby systems are required by the NEC to be electrically operated and ______ held.
Mechanically
Galvanometers are used to measure what?
Current
Retrieving oil samples from the transformer sampling cock is the preferred method because it offers the most convenience and least contamination. (T/F?)
False
Wiring diagrams should show all components in a circuit, arranged without regard to their actual physical location. (T/F?)
False
NEC Article 695 covers the required testing and maintenance of which type of equipment?
Fire Pumps
What is not caused by voltage surges?
Flicker in incandescent lamps
AC hipot source _______ plays the largest role in the amount of power required to charge the capacitance of a test specimen.
Frequency
The number of cycles completed in one second is called the?
Frequency
The least expensive overcurrent protection for a low voltage system is:
Fuse
Digital substations are based on which IEC standard?
IEC 61850
Which of the following letter designations is used to indicate that a trip unit provides overload protection?
L
With insulation resistance test equipment:
Leakage current returned by the guard lead are not normally metered
Convert the vector (5.0, 7.0) into magnitude / angle form.
Magnitude 8.6, angle 54 degrees magnitude = sqrt(x^2 + y^2) angle = tan^-1 (y/x)
