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S6-Q144.) System configuration: Three phase application with ground fault relay, the neutral is bonded to
ground at the generator. Which type of switch is best suited for this situation?

a.) 2-pole
A three phase application cannot utilize a 2-pole switch.
b.) 3-pole
Since there is a neutral, this switch would not work.
c.) *4-pole
Correct. Because of the neutral, this switch is best suited for the application.
d.) 5-pole
This would leave one pole open and not be cost effective.

S6-Q145.) All automatic transfer switches utilize which of the following basic functions?

a.) *Utility sensing, time delay to start generator, generator voltage sensing, return to normal
timer, and cool down timer
Correct. Each is necessary to maintain a quality system both for the power it provides and the
longevity of the generator/prime mover.
b.) Start contacts to generator, time delay to start generator, cool down timer, voltage regulator
Voltage regulation is done by the generator. Also, there is no cool down period provided. This could
shorten the life of the system.
c.) Utility sensing, time delay to start generator, voltage regulator, cool down timer,
manual override to normal
Voltage regulation is done by the generator.
d.) Time delay to emergency source, engine off at return to normal timer, voltage regulator, utility
sensing
Voltage regulation is done at the generator.

S6-Q146.) A Bypass Isolation/Closed Transition transfer switch is most often used on which type of load?

a.) Non-critical
The closed transition would indicate that power cannot be lost to some equipment. During generator
testing, the switch will transfer from the functioning utility to generator power.
b.) *Critical
Correct. The closed transition would indicate that power cannot be lost to some equipment.
This would indicate that equipment would be critical. During generator testing, the switch will
transfer from the functioning utility to generator power. The closed transition would provide
no interruption in service.
c.) Remote locations
The remoteness of the location really has no impact on what type of switch is used.
d.) Only three phase
There are critical single phase applications.

S6-Q147.) How many sources does a typical transfer switch have to select from?

a.) *Two
Correct. The primary and secondary. Usually this is the incoming utility and the back-up
generator.
b.) Three
While it is possible to have a back-up, back-up generator, it is not usually done and would require
special equipment.
c.) More than three
This is not practical or necessary.
d.) As many as required by local code
Local code usually does not require or govern transfer switches or sources.

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