NETA Level 2 Exam – Questions With Apposite
Solutions
Losses in a rotating machine due to heat can have a dramatic effect on
efficiency. Which category of losses has the least influence on electric motors?
Correct Answer - Friction
Core Losses: The energy required to magnetize the core and eddy current
losses in the stator core.
Stator Losses: I2R heating of the stator due to current flow in the stator
windings.
Rotor Losses: I2 heating of rotor bars as induced current flows.
Friction and Windage Losses: Bearing and air friction on the rotor shaft and
cooling fan.
Stray Load Losses: Leakage reactance fluxes induced by the load current.
Which of the following protective functions requires the least energy to trip a
circuit breaker?
L
S
I
G Correct Answer - G - ground fault
The sensing element or setting of a motor overload device that is not sufficient
to start or carry the load of a motor marked with a service factor of 1.15 or
greater shall not exceed _____ Correct Answer - 140%
What is the difference between a thermogram and a thermal image?
Correct Answer - There is no difference; both terms refer to the same thing.
How many time constants are required for circuit parameters to normally
reach their final value in an inductive circuit? Correct Answer - 5
The time it takes a fiber optic signal to travel from one point to another over a
transmission channel is called Correct Answer - Propagation delay
, True or False? With tight-buffered fiber optic cable, the buffering material
does not come in direct contact with the fiber. Correct Answer - False
Thermal relays are commonly used in motors against over-currents, which is
drawn because of: Correct Answer - Overloads
A three-phase 480-208Y/120V transformer rated 750kVA with an impedance
of 4.6% is to be protected by a circuit breaker on the primary side with fuse
protection on the secondary side. What is the maximum standard trip setting
that should be used for this breaker? Correct Answer - 2500A
NFPA70 Table 450.3(B)
According to ANSI/NETA MTS, how often should ground systems be
electrically tested assuming a multiplier of 1.0? Correct Answer - Once
every two years
Which of the following components would you not expect to find inside an
Automatic Transfer Switch? Correct Answer - Current balance relay
Generally, high current test sets: Correct Answer - Provide high test
currents at 10 volts or less
What are the risk categories used to determine maintenance and testing
procedures for SF6 gas-insulated equipment? Correct Answer - New
gas, non-arced, normally arced, and heavily arced
Calculate the percentage differential mismatch for an electromechanical relay
protecting a 138kV-69kV Delta-Wye 50MVA Transformer with 250:5 CTs on
the primary and 500:5 CTs on the secondary, with CT ratio taps on the relay
set to 5A on the high side and 9A on the low side. Correct Answer -
3.78%
When a circuit breaker is in the "test" position _______power is removed.
Correct Answer - Line
Which test method measures the Carbon Tetraflouride content in SF6 gas?
Correct Answer - ASTM D2685
Solutions
Losses in a rotating machine due to heat can have a dramatic effect on
efficiency. Which category of losses has the least influence on electric motors?
Correct Answer - Friction
Core Losses: The energy required to magnetize the core and eddy current
losses in the stator core.
Stator Losses: I2R heating of the stator due to current flow in the stator
windings.
Rotor Losses: I2 heating of rotor bars as induced current flows.
Friction and Windage Losses: Bearing and air friction on the rotor shaft and
cooling fan.
Stray Load Losses: Leakage reactance fluxes induced by the load current.
Which of the following protective functions requires the least energy to trip a
circuit breaker?
L
S
I
G Correct Answer - G - ground fault
The sensing element or setting of a motor overload device that is not sufficient
to start or carry the load of a motor marked with a service factor of 1.15 or
greater shall not exceed _____ Correct Answer - 140%
What is the difference between a thermogram and a thermal image?
Correct Answer - There is no difference; both terms refer to the same thing.
How many time constants are required for circuit parameters to normally
reach their final value in an inductive circuit? Correct Answer - 5
The time it takes a fiber optic signal to travel from one point to another over a
transmission channel is called Correct Answer - Propagation delay
, True or False? With tight-buffered fiber optic cable, the buffering material
does not come in direct contact with the fiber. Correct Answer - False
Thermal relays are commonly used in motors against over-currents, which is
drawn because of: Correct Answer - Overloads
A three-phase 480-208Y/120V transformer rated 750kVA with an impedance
of 4.6% is to be protected by a circuit breaker on the primary side with fuse
protection on the secondary side. What is the maximum standard trip setting
that should be used for this breaker? Correct Answer - 2500A
NFPA70 Table 450.3(B)
According to ANSI/NETA MTS, how often should ground systems be
electrically tested assuming a multiplier of 1.0? Correct Answer - Once
every two years
Which of the following components would you not expect to find inside an
Automatic Transfer Switch? Correct Answer - Current balance relay
Generally, high current test sets: Correct Answer - Provide high test
currents at 10 volts or less
What are the risk categories used to determine maintenance and testing
procedures for SF6 gas-insulated equipment? Correct Answer - New
gas, non-arced, normally arced, and heavily arced
Calculate the percentage differential mismatch for an electromechanical relay
protecting a 138kV-69kV Delta-Wye 50MVA Transformer with 250:5 CTs on
the primary and 500:5 CTs on the secondary, with CT ratio taps on the relay
set to 5A on the high side and 9A on the low side. Correct Answer -
3.78%
When a circuit breaker is in the "test" position _______power is removed.
Correct Answer - Line
Which test method measures the Carbon Tetraflouride content in SF6 gas?
Correct Answer - ASTM D2685
