2027/COMPLETE ACTUAL EXAM QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS)
ALREADY GRADED A+ PASS GUARANTEED
Connect a transformer with an existing transformer already in
service.
1. check nameplate making sure transformers have same
voltage, polarity, impedance, tabs, frequency.
2. Connect to the same face as the other transformer.
3 hook everything up leaving the secondary legs in the clear.
Take voltage to make sure transformer is good.
4. use voltmeter to verify which legs go
together. 5 make in break parallel on
secondary side.
6. tape bushing yellow if transformer is left paralleled.
A 37.5 kVA transformer is energized at 7200 V and has a reading
of 6 A on the primary with a secondary of 120/240. Is it
overloaded?
Yes, kVA divided by input equals 100% capacity.
Why is a transformer case grounded?
To protect ourselves and the public.
,Give two reasons for floating the neutral on a closed Y delta
transformer bank.
Protect our equipment. To prevent balancer bank action.
On a transformer nameplate the impedance reads .3% what does
this mean?
At 100% capacity the transformer will have .3% voltage loss.
What is the rule for grounding a transformer bank with a delta
connected secondary?
Ground at the point Of least potential.
What is the rule for grounding a transformer bank with a Y
connected secondary?
Ground at the point common to all three.
What is a potential transformer?
An electrical device used to bring voltage to a readable level.
,What is a current transformer?
A device that brings current to a readable level.
What must be done when working on current transformers?
Must be properly isolated and shunted.
How do you check the polarity of a transformer?
1. do not hi-pot
2. ground transformer case
3. Wear high-voltage rubber gloves.
4. check input
voltage If more
than input Add If
less than input Sub
What is polarity?
The direction of current flow in the primary windings as compared
to the direction of current flow in the secondary windings.
Do you ground the case of a book or boost transformer?
No
, If you had a blown fuse on a pad mount transformer what would
you do to replace it?
Vent tub, Pull the bayonet fuse with approved stick, and replace
fuse according to kVA of the tub. Reinstall bayonet fuse.
A 25 kVA transformer has a blown fuse. You refuse it and it blows
again. What do you do?
Isolate tub and test tub, check secondary.
What is a regulator?
An auto transformer used to keep voltage within desired
parameters.
What is a secondary?
Current carrying conductor with voltage less than 600 V.