Transformer Connection Flashcard

Front

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

Back

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

Front

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.

Back

it should be used for Delta connections only.

Front

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

Back

120/208

Front

What is the reason for connecting the secondary windings in parallel?

Back

To use the full kVA rating of the transformers.

Front

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

Back

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

Front

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.

Back

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

Front

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

Back

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

Front

Which kind of secondary service voltage requires the Wye-point on the primary to be floated? Options: 240/480, 120/208, 277/480, 240/416

Back

240/480

Front

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

Back

480

Front

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.

Back

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