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S6-Q148.) The source from which a transfer switch draws its operating power is:

a.) *The source it is currently connected to
Correct. This is the source that it is going to switch the load to. You do not want to draw
operating power from the source the switch is leaving since it has probably failed and would not
provide power to make the switch.
b.) The generator
Not necessarily. If the generator fails and the utility is available, the utility would be the choice.
c.) The utility
Not necessarily. If the utility fails, the generator would be the choice once it has stabilized.
d.) A battery
Batteries would have to be run through an inverter to produce AC.

S6-Q149.) If the phase rotation of the utility does not match the phase rotation of the generator, what will likely
be the outcome?

a.) No difference in operation of any equipment
Three phase motors will be affected.
b.) *Motors will run in reverse
Correct. Swapping phases is the technique used to reverse three phase motors. Not matching
the utility could cause catastrophic damage.
c.) Electric clocks will run backwards
Electric clocks are usually single phase and would not be affected.
d.) Generators will have to be run in reverse
This is not practical due to the prime mover not having this capability.

S6-Q150.) It is not always practical to take a facility offline (remove from utility power) to perform routine
tests of a system. What method may be employed to eliminate power interruption?

a.) *Use the transfer switch Load Test Switch
Correct. Most transfer switches have a resistive load bank which will allow load simulation
for brief periods of time.
b.) Open the building utility main breaker
This may cause unnecessary outages and damage critical equipment.
c.) Open the dedicated breaker for the transfer switch
This would not increase the load to the generator.
d.) Manually close the breaker for the transfer switch
This may cause parallel operation between the generator and the utility. This type of operation
requires approval by the utility. It would also do little to increase the load.

S6-Q151.) Changing the Main and/or Arching contacts should be done:

a.) During normal routine maintenance
The system must be taken offline for this purpose. Since the contacts are between both the utility and
load and generator and load, one is always energized and thus dangerous.
b.) *When the system is offline specifically for that purpose
Correct. The system must be taken offline for this purpose. Since the contacts are between
both the utility and load, and generator and load, one is always energized and thus dangerous.
c.) When the system is energized and online
The system must be taken offline for this purpose. Since the contacts are between both the utility and
load, and generator and load, one is always energized and thus dangerous.
d.) During a utility outage
The generator would then be energized and the contacts would still be dangerous.

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