Three-Phase Transformers and Configurations

What is the most common method utilized by utility companies for three-phase services?

• Single-phase transformer

• Interconnecting three single-phase transformers

• Two-phase transformer

• None of the above.

Fill in the blank: A three-phase transformer unit is basically three single-phase transformers inside a ______.

• Single tank

• Double tank

• Triple tank

• Quadruple tank

Fill in the blank: The kVA rating of the transformer is clearly printed on the ______.

• Front

• Back

• Side

• Top

What is the responsibility of the lineworker according to the text?

• Designing transformers

• Confirming transformer nameplate information

• Manufacturing transformers

• Selling transformers

What is the purpose of the transformer nameplate according to the text?

• To decorate the transformer

• To provide installation instructions

• To indicate transformer sizes in kVA

• To show the manufacturing date.

In a three-phase transformer, which coil is always positive?

• H-1

• H-2

• X-1

• X-3

Fill in the blank: Transformers with a primary rating of 8,660 volts and below will be rated ______ polarity.

• Additive

• Subtractive

What is the allowable range of impedance difference between transformers according to industry standards?

• 5%

• 10%

• 7.5%

• 20%

Which type of transformer connection always has a positive terminal connected to a negative terminal?

• Delta

• Wye

• Zigzag

• Star

Fill in the blank: A reversed polarity on one transformer of a three-phase bank will result in an extremely ______ current flow.

• High

• Low