Week 2 Flashcards
A nameplate reads 12,470GRDY/7,200 volts. How would this connect to a 4160/7200 system?
It can’t; it can only be connected WYE
What is a tap changer used for on a transformer?
The tap can adjust the voltage by changing the turns ratio. This ensures the proper secondary voltage is delivered to the customer.
Why is it important to perform a continuity test on a transformer before installation?
To ensure the windings are connected properly and check for shorts.
You perform a continuity test on a transformer with two H-bushings. An audible sound is heard when reading between the H1 and X1. What does this mean?
The transformer has a short between the primary and secondary windings; red tag and remove from inventory.
If a transformer nameplate has only one number listed for a primary voltage rating, how should it be connected?
Phase-to-phase
Engineers can choose from three different primary voltage designations when purchasing transformers. What are they?
Phase-to-phase only
Phase-to-phase or phase-to-ground
Phase-to-ground only
What must be done before connecting the customer’s load?
Verify the correct secondary voltage with an approved voltmeter
What information would you typically reference the nameplate for?
The primary voltage Desired secondary voltage kVA Impedances are close enough for banking and paralleling Weight of the transformer for rigging
On a transformer nameplate that lists two primary numbers separated by a slash, which number is the actual primary coil rating?
The smaller
A nameplate reads 12,470GRDY/7,200. How many primary bushings does this transformer have?
One H1; the other end of the primary winding is a tank ground
A nameplate reads 7,200/12,470Y. How would this connect to a 7,200/12,470 system?
Phase-to-ground or WYE
A nameplate reads 7,200/12,470Y. How would this connect to a 4160/7200 system?
Phase-to-phase or DELTA
