Transformer Connection Quiz

If the primary coil voltage ratings of the transformers match the _____________________, then connect _____________.

• phase-to-phase voltage of the system; Wye.

• phase-to-ground voltage of the system; Delta.

• phase-to-ground voltage of the system; Wye.

• system voltage on the work order; Wye.

During a practical session, Elijah was examining a transformer that had only one number for a primary coil voltage rating. He wondered what this indicated about its usage.

• it should be used for phase-to-ground connections only.

• the transformer can only be used for open-banks.

• it should be used on Wye systems only.

• it should be used for Delta connections only.

Ava is working on a project that involves setting up electrical systems. She needs to determine which of these service voltages on the work order require “Alley-Cat/Bad-Dog”?

• 120/208

• 240

• 120/240

• 240/480

Aiden and Sophia are working on a project involving transformers. They need to decide on the configuration of the secondary windings. What is the reason for connecting the secondary windings in parallel?

• Because the service voltage will not be correct unless we parallel the windings.

• So that we can get the voltage we need in a Delta secondary.

• To use the full kVA rating of the transformers.

• That is the only way we can get phase-to-phase for the service.

Which of these combinations best represents the connection for paralleling the windings?

• Connect “A” and “B” together to a bushing, then “C” and “D” together to another bushing.

• Connect “A” and “C” together to a bushing, and then “B” and “D” together to another bushing.

• Connect “A” and “D” together to a bushing, then “B” and “C” together to another bushing.

• Connect “A” and “C” together to a bushing, and leave “B” and “D” in place.

Harper is working on a project to supply three-phase power from an underground system. Which of these statements about using underground transformers for three-phase service is true?

• When supplying three-phase power from underground systems, the transformers used are always single units.

• The “Power” pad-mount used in an open bank configuration must have the grounding strap removed from the X2.

• Only three-phase pad-mounts may be used.

• The banking connections for three-phase units must be done externally.

Which of these statements regarding Non-Standard Connections is true?

• You can get 120/208 from single-phase Delta.

• It’s possible to get two 120/208 3-phase services from one Delta-Delta bank.

• To complete a three-phase connection, you must ground at the X2 only.

• A Delta or Wye can be grounded one time at any coil terminal and still operate properly.

Grace is working on a project that involves setting up a secondary service voltage system. She needs to know which kind of secondary service voltage requires the Wye-point on the primary to be floated. Can you help her?

• 240/480

• 120/208

• 277/480

• 240/416

James is working on a Wye-Wye transformer bank in an industrial setting. Which of the following would be a typical hotleg-to-hotleg voltage he might encounter?

• 120

• 480

• 240

• 277

Arjun is working on setting up a Wye-Wye transformer bank for a new industrial project. Which of these statements about a Wye-Wye Bank is true?

• The industry standard is to leave the X2 Idle when connecting the coils in parallel.

• The “lighter” transformer is larger in kVA than the other two.

• When connecting Wye-Wye, you must tie the Wye-point.

• Each of the three transformers provides one hotleg to deliver three-phase power.