NETA ETT Certified Level 3
What are the types of PLC languages?
* Instruction List * Structured text * Function block diagram * Ladder diagram * Sequential function chart
With electromechanical relay motor protection, what types of relays were provided for induction motor protection?
* Overcurrent * Undervoltage * Differential * Overvoltage * Current Balance * Thermal replica This was originally a 'not' question where the answers were 'Loss-of-field and sync-check' because they aren't useful for induction motor protection. To me that implies that the other answers are useful for motor protection. In my own experience, I've come across at overcurrent, current balance, and thermal replica. I'm not sure about the others.
What are the necessary requirements to operate two transformers in parallel?
* Same Phase Angle Shift * Same Polarity * Same Phase Sequence * Same Frequency https://electrical-engineering-portal.com/principles-of-transformers-in-parallel-connection-1 The original question was a 'not question'. There are other conditions which are nice to have for optimal operation but are not strictly necessary
What are the convenient (but not necessary) requirements to operate two transformers in parallel?
* Same voltage ratio and turns ratio * Same Percentage Impedance * Same KVA Rating * Same position of tap changer https://electrical-engineering-portal.com/principles-of-transformers-in-parallel-connection-1 This is a question I made up that is derived from another question asking about necessary requirements.
Per NFPA 70 Article 240.4(F), transformer secondary conductors shall not be considered to be protected by the primary overcurrent protective device. What are the exceptions?
* Single-phase 2-wire transformers * multiphase 3-wire delta-delta transformers NFPA 70 Article 240.4(F)
The operating speed of a protective relay is dependent on:
* Spring Tension * Armature core air gap * Rate of flux built up https://en.wikipedia.org/wiki/Protective_relay#Types_according_to_construction This was originally a 'not question'. This list is not necessarily conclusive. It's simply the 'incorrect' answers to the 'not question'.
In NFPA 70E Section 130.4, Shock Risk Assessment, if additional protective measures are required, what should be identified?
* The design of the electrical equipment, including its over-current protective device * Personal and other protective equipment required * the boundary requirements NFPA 70E-2018 Section 130.4(B)
A 20 MVA oil-filled transformer 138kV / 15kV, nitrogen blanketed is tripped off line by the transformer differential relay (87T) indicating a fault of the unit. An external inspection does not reveal any obvious damage. What type of test(s) would be used to advise the owner as to the cause of the trip?
* Total combustible gas (TCG) * Insulation-Resistance * Transformer turns ratio * Winding-resistance This question was originally an 'all of the above' question. The question seems to imply that the 4 choices that comprise 'all of the above' are the only tests that should be used for determining the cause of the trip. This may or may not be true. Know that several different transformer faults can cause a differential relay to trip. Therefore, several types of tests my be needed to determine the cause of the trip.
What are the methods for reducing clearing time (and thus arc energy) in circuit breakers?
* Zone-selective interlocking * Differential relaying * Energy-reducing maintenance switching with local status indicator * Energy-reducing active arc flash mitigation system * An instantaneous trip setting. Temporary adjustment of the instantaneous trip setting to achieve arc energy reduction shall not be permitted. * An instantaneous override *An approved equivalent means NFPA 70-2017 Article 240.87(B)
What are some rules of thumb when concerning arc flash?
* incident energy decreased by the inverse square of the distance * Incident energy is proportional to time * Incident energy is inversely proportional to the short circuit current
In a circuit breaker, if the insulation resistance reading between a phase terminal and the frame is poor, the probable cause would be:
* moisture * dirty insulation surface * carbon or copper particles sticking to the internal surface 'any of the above' question originally. This list in not exhaustive.
How much leakage is allowed in SF6 circuit breakers per NETA-ATS?
0 ppm
What is the maximum acceptable neutralization number for a new 35kV power transformer filled with FR3 insulating liquid that was tested in accordance with ASTM D974?
0.03 mg KOH/g NETA ATS-2017 Table 100.4.3
In modem EHV circuit breakers, the operating time between the instant of receiving a trip signal and final contact separation is approximately:
0.03 sec http://www.engineeringenotes.com/electrical-engineering/circuit-breakers/circuit-breakers-operation-and-mounting-devices-electrical-engineering/33094
What is the cell voltage deviation from the bank average that indicates an equalizing charge is needed?
0.05 volt NETA MTS-2019 Section 7.18.1
What is the voltage rate of rise for an ASTM D1816 test?
0.5 kV/s https://hvtechnologies.com/which-oil-testing-standard-should-you-choose-to-determine-dielectric-breakdown-voltage/
The light source used to field test arc-flash detection relays generally needs to have an output duration of ____ ms, or more.
1 https://cdn.selinc.com/assets/Literature/Publications/Technical%20Papers/6518_VerifyPerformance_MZ_20110915_Web2.pdf?v=20151125-083547
The residual voltage of a capacitor, rated not over 1,000V, shall be reduced to 50V or less within ______ after the capacitor is disconnected from the source of supply.
1 minute NFPA 70 Article 460.6(A)
What is the maximum allowable time delay result for a ground fault relay?
1 sec at 3000 amps NFPA 70-2017 Article 230.95(A)
A secondary tie of a transformer is a circuit operating at _____, nominal, or less, between phases that connects two power sources or power-supply points.
1,000V NFPA 70-2017 Section 450.6
What is the NETA-MTS recommended minimum insulation resistance value for 5kV vacuum circuit breaker?
1.5 Gigohm NETA MTS-2019 Table 100.1
Polarization index is defined as the ratio of the measured insulation resistance at what two specific times?
10 minutes to 1 minute
How many pounds of PCB must a spill exceed for the responsible party to be required to notify the appropriate EPA regional office?
10 pounds 40 CFR 761.125
Zigzag transformers consist of two windings that are ____ degrees out of phase.
120 https://testguy.net/content/324-ETT-III-Transformers
A seprate overload device for a 2HP 3-phase induction motor with a service factor of 1.15 shall be rated at no more than _____ of the motor nameplate full-load current rating.
125% NFPA 70-2017 Article 430.32(A)(1)
Calculate the capacitance of a 4160V, 60 Hz capacitor bank rated 100kVAR with a Xc of 173.05 ohms.
15.328 F C = 10^6 / (2 * pi * f * Xc)
The number of pilot wires required for protecting 3-phase transmission lines using Translay method of protection is:
2 http://www.yourelectrichome.com/2011/09/differential-protection-of-feeders.html
One set of service-entrance conductors, either overhead or underground, is permitted to supply ____ service disconnecting means in lieu of a single main disconnect.
2 to 6 NFPA 70-2017 Article 230.71(A)
What is the minimum acceptable PI value for a newly installed 200kW emergency generator per NETA standards?
2.0* NETA ATS-2017 Section 7.22.1.D.1.1
What is the expected VA rating @ 5A for a current transformer with a burden designation of B0.1, per IEEE C57.13?
2.5 Review IEEE C57.13 standard burdens
What would be the most suitable insulation power-factor test voltage for a 4.16kV dry-type transformer winding?
2kV https://testguy.net/content/369-Power-Factor-Testing-Voltage-Considerations-Explained
Conduits and raceways, including end fittings, shall not rise more than ____ above the bottom of a switchboard enclosure.
3 in NFPA 70-2017 Section 408.5 Know NFPA 70
What peak test voltage would you use to perform a VLF test on service aged cable rated 25kV according to NETA standards?
33kV NETA MTS-2019 Table 100.6.3 http://testguy.net/content/278-Power-Cable-Testing-and-Diagnostics-Overview#vlf Know NETA tables
Convert Peak to RMS Voltage: 500 V
353.50V
A given 600V panelboard is fed by a transformer with an available fault current of 24,000A and is protected by a circuit breaker with a fault clearing time of 0.025 seconds. According to NFPA 70E, which of the following would be considered an acceptable flash protection boundary for this equipment?
36 inches NFPA 70E-2018 Table 130.7(C)(15)(a) Know NFPA 70E
What is the NETA-MTS recommended maximum AC test voltage for hipot testing single-phase 15kV automatic circuit reclosers with a rated impulse withstand voltage of 110kV?
37.5kV NETA MTS-2019 Table 100.15
A right triangle has one side of 5 and another side of 4 (neither side is the hypotenuse). What is the angle adjacent to the side that is 5?
38.66 deg* Adjacent Angle = -tan(opposite / adjacent)
The base temperature used in temperature correction for motor insulation resistance is:
40 C Field Testing of Motors, IEEE 43
A CT supplies multiple devices. To confirm which devices are connected to it, the output of a single phase 5A source is connected to the X1 terminal of the CT without removing the existing wiring. The expected current at each correctly connected device would be:
4A to 5A, because the CT winding impedance is much higher than the connected load impedance.
What size neutral resistor would be required to limit the fault current of a 13,800-480Y/277V 1500kVA Transformer to 5A?
55.4 Know Ohm's Law. 277 V / 5A = 55.4 ohms I believe that since this is dealing with the neutral, Line-Neutral voltage (277 V) should be used in the formula. 5 A on the line will also be 5A on the windings since the transformer configuration is a Wye configuration. I also believe that the impedance of the transformer is negligible in this calculation since it isn't mentioned in the question and presumably would only limit the fault current further.
Where the supplemental electrode is a rod, pipe, or plate electrode, that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than _____ awg copper wire.
6 AWG NFPA 70-2017 Article 250.53(E)
Where multiple rod, pipe or plate electrodes are installed to augment a rod with a resistance greater than 25 ohms, they shall be not less than ____ apart.
6 feet NFPA 70-2017 Article 250.53(B)
Measuring from the floor, what is the minimum height required for a working space in front of a 480Y/277V 1200A switchboard according to the National Electric Code?
6.5 ft NFPA 70-2017 Article 110.26(3)
A disconnecting means should be provided for all ungrounded conductors derived from stationary battery system over ____ volts.
60 NFPA 70-2017 Article 480.7(A)
A given 480V motor control center is fed by a transformer with an available fault current of 48kA and is protected by a circuit breaker with a fault clearing time of 0.025 seconds. According to NFPA 70E, which of the following would be considered an acceptable flash protection boundary for this equipment?
60 inches NFPA 70E-2018 Table 130.7(C)(15)(a)
You have fiber optic cable attached to the relay you are testing. What is most likely inscribed on the outer jacket?
62.5/125 https://en.wikipedia.org/wiki/Multi-mode_optical_fiber
Which is the "Can't Let Go" range of current flow?
9-25 mA
Which insulating fluid test would furnish a better evaluation of changes that may occur in the oil from transformers and load tap changers?
ASTM D1816 IEEE C57.106 Section 5.2.1
Which test method measures Hydrolyzable Flouride content in SF6 gas?
ASTM D2284 [Standard Test Method for Acidity of Sulfur Hexafluoride] NETA ATS-2017 Table 100.13 Know the ASTM test names what what they test
According to IEEE C57.106, which test is recommended for routine acceptance of new, unprocessed oil from a supplier for use in circuit breakers?
ASTM D877 [Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes] https://hvtechnologies.com/which-oil-testing-standard-should-you-choose-to-determine-dielectric-breakdown-voltage/ Know IEEE C57 information. Know ASTM tests and definitions
Which of the following statements is correct with regards to ground fault protection for a 480V, 1200A, solidly grounded emergency system?
An audible and visual signal is required NFPA 70-2017 Article 700.6 This is just for testguy purposes. To know the answer to this question, you must know NFPA 70 requirements for emergency systems. Basically, in emergency systems, ground fault protection isn't required for equipment with automatic disconnecting means. But what is required is some audible/visible signal that a ground fault has occurred.
What is the Restricted Approach Boundary for a 50V system?
Avoid contact NFPA 70E-2018 Table 130.4(D)(a)
A bus with 24kA available fault current is to be equipped with 400/5A current transformers connected to a protective relay with a total secondary burden of 0.33 ohms. What class CT should be chosen to ensure that these CT's do not saturate under maximum fault conditions?
C200 https://www.powellind.com/sites/downloads/ProductAssets/01.4TB.062%20Choosing%20Current%20Transformers%20for%20Relaying%20Use.pdf
The voltage induced into the armature of a DC motor is known as the:
CEMF [counter-electromotive force] https://en.wikipedia.org/wiki/Counter-electromotive_force
Using the figure shown, choose which curve best represents the capacitance charging current measured during DC testing of insulation.
Curve A https://www.testequipmentdepot.com/megger/pdf/electrical-insulation-testing_guide.pdf Capacitance Charging Current is defined as 'Current that starts out high and drops after the insulation has been charged to full voltage (much like water flow in a garden hose when you first turn on the spigot).
If you are a crew leader, what is the next thing you would do to maintenance test a transformer after a job safety assessment has been completed and the hierarchy of risk control has been implemented?
De-energize the transformer Isolate via LOTO Complete a job safety assessment Gather the crew for a job briefing*
A negative sequence relay is used to:
Determine if the generator is supplying an unbalanced load. https://testguy.net/content/331-ETT-III-Protective-Relays
True or False. Every Scada system is unique to its environment, so there is no need to be consistent with colors, symbols and terminology.
False
The alternate source for emergency systems are required by the NEC to have ground-fault protection of equipment.
False NFPA 70-2017 Article 700.31
When conducting an ASTM D877 dielectric breakdown test, the fluid is continuously stirred. True or False
False https://hvtechnologies.com/which-oil-testing-standard-should-you-choose-to-determine-dielectric-breakdown-voltage/ Know ASTM tests and definitions. Know IEC tests and definitions. Some dielectric breakdown tests require stirring, some don't. I guess the point of the question is to test knowledge of which of these tests involve stirring. It is probably also useful to know the other differences between the tests. The tests are ASTM D877, ASTM D1816, and IEC 60156.
Define: Not readily accessible to persons unless special means for access are used.
Isolated NFPA 70 Article 100
The Ferranti effect is experienced on a long overhead transmission line when it is:
Lightly loaded https://en.wikipedia.org/wiki/Ferranti_effect
A trip latch check switch (T/LCS) functions to _____________.
Mechanically prevent the breaker from closing unless the trip latch returns to its reset position. http://testguy.net/content/150-Circuit-Breaker-Terminology#latch_check_switch
What gas would indicate partial discharge in transformer oil?
Methane testguy.net seems to indicate that this is the correct answer. I think hydrogen
Which standard addresses equipment grounding?
NFPA 70
A newly installed 4160V emergency generator has an insulation resistance value of 150 Megohms after one minute with an equipment temperature of 32 degrees C. Is this value acceptable per NETA standards?
No NETA ATS-2017 Table 100.11 https://testguy.net/content/240-Insulation-Resistance-Test-Values Know the NETA-ATS Insulation Resistance tables
When may circuit breakers be installed in parallel for a single load?
Only when factory assembled NFPA 70-2017 Article 240.8
Thermal relays are commonly used in motors to protect them against:
Overloads* https://www.electrical4u.com/thermal-relay-working-principle-construction-of-thermal-overload-relay/
What effect does sustained voltage above the voltage where PD begins have on XLPE cable?
Possible further deterioration https://testguy.net/content/325-ETT-III-Cables
Reverse power relays operate under what conditions?
Reversal of current flow and phase angle falling in the operate zone.
Which Subpart of OSHA 29 CFR 1910 addresses electrical safety?
S https://www.osha.gov/pls/oshaweb/owasrch.search_form?p_doc_type=STANDARDS&p_toc_level=1&p_keyvalue=1910
How should metal-enclosed, medium-voltage interrupter switches be operated?
Stored energy https://testguy.net/content/323-ETT-III-Switchgear-and-Switchboard-Assemblies
Which is the correct definition of TDD as put forth in IEEE 1159?
TDD is the total rms harmonic current distortion, in percent of the maximum demand load current (15 or 30 min demand).
Meter Sockets and meter disconnect switches should generally be connected on what side of a service disconnecting means?
The line side NFPA 70-2017 Article 230.82(3) https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=40.0 This was originally a True/False statement question. The answer stated that the load side is wrong. The reference above seems to imply that meter sockets and meter disconnect switches should generally be connected on the line side. Know NFPA 70
During the acceptance test of a 300HP 5kV AC induction motor, a PI value of 1.5 was obtained. Based on your knowledge of NETA standards, what can you conclude from this reading?
The readings are unacceptable and should be investigated. NETA ATS-2017 Section 7.15.1.D.2.1
In a directional comparison blocking (DCB) scheme, why is a communications signal transmitted?
To communicate to the remote end that the fault is in the reverse direction of the local end* http://peguru.com/2011/04/directional-comparison-blocking-scheme/
Fiber optics have a large capacity to carry high speed signals over longer distances without repeaters than other types of cables.
True https://testguy.net/classroom/advantages-of-fiber-optics.pdf
Resistance in a circuit will cause a delay in the time required for charging a capacitor.
True https://www.electronics-tutorials.ws/rc/rc_1.html
When can you remove dead break elbows?
When de-energized
In the National Electrical Code, the current carrying abilities of conductors are called the
ampacities NEC
To reverse the direction of rotation of a three-phase motor, reverse:
any two leads
Entering a permit space can prove fatal for an employee when the O2 level is:
below 19.5 percent or above 23.5 percent
Correcting the power factor of three-phase loads normally involves adding (capacitance, inductance) in (series, parallel)
capacitance in parallel http://archive.is/WOiLd Typically, power factor is offset by increased inductance. Adding capacitance in parallel corrects this.
Fuseholders for cartridge fuses shall be so designed that it is difficult to put a fuse of any given class into a fuseholder that is designed for a _____ lower or a _____ higher than that of the class to which the fuse belongs.
current / voltage NFPA 70-2017 Article 240.60(B
In an alternator, when the rotor DC excitation current is removed there is a possibility of damaging high voltages being developed. In order to limit voltage and thereby prevent damage, a _____ or a diode can be included in the circuit.
field discharge resistor http://archive.is/IDuB0
Identify the optional maintenance inspection for medium- and high-voltage shielded cable per NETA specs.
fireproofing The other answers are assumed to be mandatory (as opposed to optional) and they are jacket, terminations, connections, and supports. NETA MTS-2019 Section 7.3.3.A
Class 3 rubber insulating gloves are proof tested at 30,000 VAC, what color label would you expect to find on these gloves?
green
Feeder breakers in a hospital with a 3000A 480V service, which serve critical care, are required to have?
ground fault NFPA 70-2017 Article 517.17
As a battery cell starts discharging, internal resistance of the cell will _____ .
increase http://batteryuniversity.com/learn/article/discharge_methods Link leads to a paywall. The reason why the internal resistance increases appears to have to do with change in electrolyte concentration.
Differential relays are used for the protection of transformers, induction motors, busbars and alternators against:
internal faults
In an RC parallel circuit, the current through the resistor and the current through the capacitor are
less than 90° out of phase with the resistor current lagging https://www.allaboutcircuits.com/textbook/alternating-current/chpt-4/parallel-resistor-capacitor-circuits/
One of the main functions of personal protective grounds is to provide a _______ impedance path for a short circuit.
low https://testguy.net/content/269-Applying-and-Removing-Protective-Grounds
According to NETA-ATS, an insulating gas analysis on a SF6 switch would include:
moisture tension NETA ATS-2017 TAble 100.13 Know the NETA tables
Time delay fuses are used in the protection of which of the following:
motors https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/solution-center/bus-ele-tech-lib-fuses-time-delay.pdf
What is used to suppress the reverse polarity voltage spike in an electrical relay?
resistor
If one phase of voltage to a three-phase motor opens, the motor may slow down, overheat, or possibly stop. This condition is known as
single phasing https://www.marineinsight.com/marine-electrical/single-phasing-in-electrical-motors-causes-effects-and-protection-methods/
In a three-phase motor, the speed of rotation of the magnetic field is called the _____________ speed.
synchronous
The presence of a Run Speed or RPM spike in a Demodulation Spectrum is a result of _______.
unbalance or misalignment
What two qualities are usually measured with a circuit breaker motion analyzer?
velocity and displacement