Transformers

Question 1

What are 3 types of transformers

Answer 1

Isolation Transformer
* Autotransformer
* Current transformer (a clamp on ammeter is an example of use of a current transformer)

Question 2

Fuel fired equipment is restricted to what Volt control circuits

Answer 2

Fuel fired equipment is restricted to 120 Volt control circuits

Question 3

Primary and secondary winding in a control power transformer is H or X?

Answer 3

The most common type of
control transformer has
two primary windings (H1-
H2 and H3-H4) and one
secondary winding (X1-X2).
Note that the primary
windings are crossed.

Question 4

What is the critical rating used to size the CPT.

Answer 4

This inrush VA is the critical rating used to size the CPT.

Question 5

what are the transformers voltage rating for ignition transformer for gas and oil appliances

Answer 5

Typical - 6 000 V for natural gas/propane
- 10 000 V for #2 fuel oil

Question 6

A gap of what inch range between the
ignition electrode and burner
ground should be maintained.

Answer 6

A gap of 1/8” to 5/32” between the
ignition electrode and burner
ground should be maintained.

Question 7

What is the voltage limitation on the secondary side of a control power transformer for a safety control circuit of a gas fired appliance?

Answer 7

120 V

Question 8

What is the primary purpose of the design of an isolation transformer?

Answer 8

To physically and electrically separate primary and secondary windings from each other.

Question 9

What type of transformer is used for power conditioning?

Answer 9

Isolation transformer

Question 10

What is protected by fusing the secondary side of a control power transformer?

Answer 10

The transformers secondary winding

Question 11

What information is required from the loads energized to size a control power transformer?

Answer 11

Total inrush VA

Question 12

What is the minimum ignition transformer secondary voltage required for direct spark ignition of main burner gas?

Answer 12

6000 V

Question 13

What is the minimum ignition transformer secondary voltage required for ignition of an oil burner?

Answer 13

10000 V