140204a

Question 1

-What is a transformer?

Answer 1

It’s an electrical device that changes the voltage, amperage and polarity of alternating current from one value to a more convenient value.

Question 2

What does the hvac/r trade uses transformer for?

Answer 2

Reduce line voltage to provide lower voltage power for control systems

Increase line voltage to a very high value to provide a spark for ignition systems

Power multiple devices from a single source

Question 3

What is the purpose of a voltage reducing transformer? and why is it important?

Answer 3

This device is used to reduce voltage of refrigeration and air conditioning control circuits. It’s important because it is safer and less expensive to make than a line voltage control circuit.

Question 4

What is another name for voltage reducing transformer?

Answer 4

Step down transformer

Question 5

What voltages do most step down transformers reduce?

Answer 5

600 VAC to 120 VAC to a control system voltage of 24 VAC

Question 6

What is a voltage increasing ignition transformer used for?

Answer 6

It is used to provide a high voltage potential for a spark to ignite a burner for gas fired equipment

Question 7

What is another name for voltage increasing ignition transformers?

Answer 7

Step up transformer

Question 8

How much voltage does high voltage output ignition transformers supply?

Answer 8

6,000 volts to 30, 000 volts.

Question 9

What is a circuit isloation transformer?

Answer 9

it is deisgned to limit the amount of current being provided to thier secondary circuit. (Safety device)

Question 10

can a circuit isloation transformer decrease or increase voltage?

Answer 10

No it can not.

Question 11

What happens when alternating power changes direction?

Answer 11

Another magnetic field builds and induces the eletrons in the secondary winding to move in a reverse direction

Question 12

What is the laminated iron core?

Answer 12

A laminated core amplifies and direct lines of magnetic flux to increase the efficiency of a transformer.

Question 13

What reduce eddy currents and hysteresis in a transformer?

Answer 13

Laminated iron core

Question 14

What are eddy currents?

Answer 14

They are circular induced currents that interfere with the lines of magnetic flux

Question 15

What are current transformers used for?

Answer 15

They are used to prove that a motor is running to act as an interlock for safety circuits.

Question 16

What letter is used to represent the high voltage side of a transformer?

Answer 16

H

Question 17

What letter is used to represent the low voltage side of a transformer?

Answer 17

X

Question 18

What are multi tap auto Transformers designed for?

Answer 18

They are designed to accept more than one input voltage and output voltage. This allows one transformer to be used in multiple applications.

Question 19

What kind of polarity occurs when the X1 terminal is diagonally opposite of the H1 terminal?

Answer 19

Addictive polarity

Question 20

What kind of polarity occurs when the X1 terminal is directly opposite of the H1 terminal?

Answer 20

Subtractive polarity

Question 21

Which type of transformer has one winding?

Answer 21

Autotransformer

Question 22

What is hysteresis?

Answer 22

It is the heat due to the friction between the lines of magnetic flux and the molecules of the core.

Question 23

What is another name for current transformers?

Answer 23

Dough-nut

Question 24

What is the name of the transformer that the Canadian electrical code classifies as a class 2 transformer?

Answer 24

Current limiting transformer

Question 25

What transformers can be used with one or more primary voltages to provide one or more voltages to secondary voltages

Answer 25

Multi-tap and multiple winding transformer.

Question 26

What type of induction does isloation transformers use?

Answer 26

mutual induction

Question 27

What is opposite instantaneous polarities?

Answer 27

It’s when the primary AC current gets out of phase by 180 electrical degrees with the secondary current.

Question 28

What kind of induction does an autotransformer have?

Answer 28

Self induction

Question 29

Which type of transformer does not cause a phase shift between the primary and secondary power?

Answer 29

Auto transformer/ single winding transformer.

Question 30

What is the Maximum capacity the Canadian electrical code allow for the current limiting transformer? (VA)

Answer 30

100 VA

Question 31

What happens to primary and secondary power of a current limiting transformer when magnetic saturation takes place

Answer 31

The primary and secondary can not increase current nor their lines of magnetic flux.

Question 32

What are transformer voltage taps?

Answer 32

They are eletrical connections that run along side of the transformer secondary or primary winding, these taps allow access to the windings

Question 33

What happens if you connect high voltage to the low voltage side of a transformer?

Answer 33

You will burn out the winding very quickly.

Question 34

what type of electrical polarity test should you use for intermittent pilot ignition control modules?

Answer 34

subtractive polarity test to confirm its secondar voltage polarity

Question 35

What are the 3 basic types of single phase transformers?

Answer 35

Isolation transformer, single winding, and current transformer

Question 36

What is a current transformer?

Answer 36

It’s a transformer that is used as a sensor and has no iron core

Question 37

How is counter electromotive force losses created and how does it cause losses

Answer 37

It is created by the self induction in each transformer winding. It causes losses by restricting current flow, this is lost as heat from the transformer.

Question 38

What causes inductive reactance losses?

Answer 38

It is caused by the the lines of magnetic flux in the primary winding and not the secondary winding. This lost occurs because it does not induces a voltage in the secondary winding.

Question 39

What would occur if you transformer has incorrect polarity?

Answer 39

It can burn out an electronic board

Question 40

What is transformer polarity?

Answer 40

It’s the direction of the primary voltage of the transformer compared to the direction of its induced secondary voltage.

Question 41

What is winding resistance losses or cooper losses?

Answer 41

It’s the energy used by copper to resist against current flow in both the primary and secondary windings

Question 42

Name the 2 core losses

Answer 42

Eddy currents and hysteresis

Question 43

Name the 3 winding losses in transformers?

Answer 43

Copper or winding losses, inductive reactance losses and counter electromotive force losses.

Question 44

What transformer and what winding should you ever put a fuse?

Answer 44

Step up ignition transformers on their secondary winding.