Page 84 - Apprentice Manual_Neat

S3-Q68.) Airflow through a generator should never come from:

a.) The rear to the flywheel housing
This would be a more preferred path.
b.) *The flywheel housing to the rear
Correct. This would cause engine heat to enter the generator housing and would not be
desirable.
c.) A remote source
Generally, this is a desired source of cooling air.
d.) Generators are typically explosion proof and require no airflow
Generators usually must have clean cool airflow to cool the current carrying conductors, bearings,
and rotor.

S3-Q69.) A restive load bank connected to a generator would best be used for which of the following
purposes?

a.) Test engine cooling
Yes, a load bank can be varied to simulate varying loads. This would impact the engine horsepower
and thus cooling.
b.) Test engine performance
Yes, a load bank can be varied or dwelled to monitor efficiencies, fuel consumption, or recovery.
c.) Clean a diesel engine from “wet-stacking”
Yes, increasing horsepower output can stop diesel wet-stacking.
d.) *All of the above
Correct. All of the above answers are benefits of using a load bank for testing.

S3-Q70.) What is the maximum desired current @ 80% load for a 15KW single phase 120/240 volt
generator?

a.) *50 amps
Correct. (15,000W * 0.80)/240V = 50A.
b.) 110 amps
Incorrect response (see answer a).
c.) 80 amps
Incorrect response (see answer a).
d.) 25 amps
Incorrect response (see answer a).

S3-Q71.) What is the desired maximum current @ 100% load for the following three phase generator?
PF=0.85, KW=350, V=480.

a.) 857 amps
Incorrect response (see answer c).
b.) 300 amps
Incorrect response (see answer c).
c.) *495 amps
Correct. (V)*(A)*(√(3))*(PF) = KW, (480)*(A)*(1.732)*(0.85) = 350,000=495
d.) 1143 amps
Incorrect response (see answer c).

EGSA Apprentice Certification Program Study Guide - Page 76