Transformers Week 3

the power leg is always located _______________ away from the neutral connection.

• closest

• 3 coils

• 1-1/2 coils

• next to

either a ____________ or a physical check by taking the lid off the transformer is needed to check which configuration the secondary coils are in

• megger

• voltage

• turns-ratio

• continuity

when banking transformers, using transformers of differing polarity will not work

• True

• False

what needs to be done if you have transformers with mismatched impedances between paralleled units or banks

• cannot use

• de- rate because voltage will change

• doesn't matter

• de-rate because load will not divide in proportion to the KVA

a single three phase transformer is the most common choice among utilities for providing three phase power

• true

• false

open banks are about _________ % as efficient as a three pot bank

• 52.7

• 47.3

• 57.5

• 57.7

proper transformer selection starts with what?

• looking at KVA rating

• comparing the circuit and service voltages with the transformers voltage rating

• reviewing the transformer nameplate

• comparing when on the pole

if transformers of different impedance are banked together the highest impedance transformer will supply a greater share of the load and possibly end up being overloaded.

• true

• false

the secondary coils must be ________ for wye secondary connections, so the full kva rating of the transformer is utilized.

• doubled

• paralleled

• the same

• connected

which of these is a useless connection

• open wye, open delta

• open delta, open delta

• open delta, open wye