Transformers

Question 1

Which machine permits the transfer of electrical energy between 2 circuits that are completely insulated from eachother.

Answer 1

Transformer

Question 2

Which winding in a transformer receives energy inductively from the other.

Answer 2

The secondary winding

Question 3

If the secondary winding has more turns than the primary what type of transformer is it?

Answer 3

It would be a step up transformer.

Question 4

In transformers what must always exist between the primary and secondary fields to maintain the required primary current for the load and losses.

Answer 4

A balanced condition must exist between the windings.

Question 5

The power transformer transfers electrical energy from one circuit at a certain frequency and voltage to a second circuit at the same frequency and a different voltage.

Answer 5

True

Question 6

What type of ac machine are transformers classified as?

Answer 6

Static ac machine.

Question 7

Transformers used to step current down are known as?

Answer 7

Current transformers.

Question 8

What should never be done to the secondary terminals of a potential transformer?

Answer 8

They never be short circuited because a heavy current will flow,burning out the windings.

Question 9

What type of transformer only has one winding?

Answer 9

Autotransformers.

Question 10

What type of transformer only has one winding?

Answer 10

Autotransformers.

Question 11

In a core type transformer, a section of the both windings are wound on each leg of the core, with the secondary winding wound next to the core and the primary winding wound over the secondary.

Answer 11

True.

Question 12

What causes the heat in a transformer?

Answer 12

The hysteresis of the magnetic material or friction of the molecules.

Question 13

Due to the alternating magnetic fields in a transformer, the iron losses occur when?

Answer 13

Whenever the primary is energized, even with no load.

Question 14

How are transformers usually rated?

Answer 14

Classified as volt-amperes (va), in kilo-volt amps (kva), or mega-volt amps (mva).

Question 15

Describe a conservator system on a transformer?

Answer 15

It acts as a barrier to prevent the atmosphere from contacting the oil in the main tank, preserving the dielectric strength.

Question 16

How many types of main lead entrances are there for bushings.

Answer 16

4 types

Question 17

Series street lighting systems require what type of transformer to function correctly.

Answer 17

They require a constant current transformer to supply a constant current source.

Question 18

Describe generator and transformer windings connected in a wye setup.

Answer 18

Any two lines will be 1.732 times the phase voltage and the line current will be the same as the phase current.

Question 19

When the primary is energized, the secondary of a potential transformer should never be shifted and the secondary of a current transformer should never be opened.

Answer 19

True