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1

Made by connecting one end of each winding.

Wye connection

2

Line and phase ____ are the same in a wye connection.

Currents

3

In a wye-connected system, the line voltage is higher/lower than the phase voltage by 1.732.

Higher

4

Three-phase voltages are ____ degrees out of phase with each other.

120

5

Delta connections are made by ____ separate inductive loads being connected.

3

6

T/F In a delta connection, line and phase voltages are different.

F, they are the same.

7

T/F In a delta connected system, the line current is lower than the phase current by 1.732.

F, higher

8

If line values of voltage (E) and current (I) are known, apparent power is calculated by:

VA = 1.732 x E (line) x I (line)

9

If phase values of voltage (E) and current (I) are known, apparent power is calculated by:

VA = 3 x E (phase) x I (phase)

10

Three phase watts (P) is calculated by:

P = 1.732 x E (line) x I (line) x PF
(PF = 1 unless otherwise stated)

P = 3 x E (phase) x I (phase) x PF
(PF = 1 unless otherwise stated)

11

T/F Wye connections are characterized by the fact that 1 terminal of each of the devices is connected together.

T

12

What is a magnetically operated machine that can change values of voltage, current and impedance without a change of frequency?

Transformer

13

What are the 3 transformer classifications?

isolation transformer
autotransformer
current transformer

14

Are all values of a transformer proportional to its turns ratio?

Yes

15

Turns ratio example:

4:1 means 4 turns of primary winds to 1 secondary wind

16

N(P)

# of turns in primary winding

17

N(S)

# of turns in secondary winding

18

E(P)

Primary voltage

19

E(S)

Secondary voltage

20

I(P)

Primary current

21

I(S)

Secondary current

22

Transformer formulas

EP/ES = NP/NS
EP/ES = IS/IP

23

Where is the power input winding connected to incoming power supply (generator side)?

Primary winding

24

Where is the load or output winding connected to driven load?

Secondary winding

25

T/F In an isolation transformer, the secondary winding is physically and electrically isolated from primary winding.

T

26

What is it called when a coil induced a voltage into itself?

Self-induction

27

The ____ current is the amount of current required to magnetize the core of the transformer.

Excitation

28

T/F Mutual induction is the ability of two coils to induce a voltage into another coil.

F, one

29

What is a step-down transformer?

A transformer that has a lower secondary voltage than primary.

30

What is a step-up transformer?

A transformer that has a secondary voltage than primary.