Level 3 NETA ETT Electrical Testing Technician
Certification Exam 2025/ NETA ETT LEVEL 3
Certification Test 2025 With 290 Questions With
Correct Answers And Detailed Rationales/ Neta Ett
Certified Level 3 Exam
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.
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)
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
pg. 1
,NFPA 70-2017 Article 250.53(B)
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.
The Ferranti effect is experienced on a long overhead transmission line when
it is:
Lightly loaded
https://en.wikipedia.org/wiki/Ferranti_effect
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
pg. 2
,disconnecting means. But what is required is some audible/visible signal that a
ground fault has occurred.
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/
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 cell voltage deviation from the bank average that indicates an
equalizing charge is needed?
0.05 volt
NETA MTS-2019 Section 7.18.1
Which is the “Can’t Let Go” range of current flow?
9-25 mA
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
What are the methods for reducing clearing time (and thus arc energy) in
circuit breakers?
pg. 3
, * 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)
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
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)
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%20Choos
ing%20Current%20Transformers%20for%20Relaying%20Use.pdf
pg. 4
Certification Exam 2025/ NETA ETT LEVEL 3
Certification Test 2025 With 290 Questions With
Correct Answers And Detailed Rationales/ Neta Ett
Certified Level 3 Exam
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.
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)
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
pg. 1
,NFPA 70-2017 Article 250.53(B)
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.
The Ferranti effect is experienced on a long overhead transmission line when
it is:
Lightly loaded
https://en.wikipedia.org/wiki/Ferranti_effect
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
pg. 2
,disconnecting means. But what is required is some audible/visible signal that a
ground fault has occurred.
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/
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 cell voltage deviation from the bank average that indicates an
equalizing charge is needed?
0.05 volt
NETA MTS-2019 Section 7.18.1
Which is the “Can’t Let Go” range of current flow?
9-25 mA
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
What are the methods for reducing clearing time (and thus arc energy) in
circuit breakers?
pg. 3
, * 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)
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
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)
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%20Choos
ing%20Current%20Transformers%20for%20Relaying%20Use.pdf
pg. 4
