NETA Power Systems Analysis & Troubleshooting 4

Question 1

A voltage unbalance exceeding NEMA's recommended 1% limit on a three-phase induction motor will result in:

Accepted Answer

Increased motor heating and reduced lifespan

Answer

Improved motor efficiency at partial load

Answer

Higher starting torque on the affected phase

Answer

Lower no-load current draw

Question 2

When performing a ground grid resistance test using the fall-of-potential method, the remote current electrode should be placed at a minimum distance of:

Accepted Answer

At least 5 times the maximum grid dimension

Answer

10 feet from the grid edge

Answer

Equal to the diagonal of the grid

Answer

Directly over the grid center

Question 3

In a distance relay (ANSI 21), the reach setting defines the:

Accepted Answer

Impedance boundary up to which the relay will trip

Answer

Maximum load current the relay will tolerate

Answer

Operating time in seconds at rated current

Answer

Minimum fault current for relay pickup

Question 4

The purpose of the NETA Acceptance Testing Specification (ATS) is to:

Accepted Answer

Establish performance criteria for newly installed electrical equipment

Answer

Define maintenance intervals for energized equipment

Answer

Set maximum allowable fault current levels for equipment

Answer

Provide guidelines for relay coordination studies

Question 5

A sudden pressure relay (ANSI 63) on a transformer trips when it detects:

Accepted Answer

A rapid rise in internal gas or oil pressure due to an internal fault

Answer

Transformer overtemperature above the alarm threshold

Answer

Loss of cooling fan operation

Answer

Tap changer mechanical failure

Question 6

When testing a low-voltage power circuit breaker, the purpose of the long-time delay test is to verify:

Accepted Answer

That the overload element will trip within the manufacturer's time-current curve tolerance

Answer

The breaker's instantaneous trip threshold

Answer

The contact resistance under rated load conditions

Answer

The dielectric withstand capability of the insulation

Question 7

On a power system one-line diagram, a dashed line connecting two buses typically represents:

Accepted Answer

A normally open tie circuit that can be closed to restore service

Answer

A high-impedance grounded neutral connection

Answer

A cable circuit rated above 35 kV

Answer

A metering connection for revenue measurement