Transformers

Question 1

Transformers - ____

What is it?

Answer 1

magnetic coupling, isolates

Question 2

Winding - voltage up, current ___

Winding - voltage ___, current up

Both winding has different power. True or False

Answer 2

down, down

False. They have the same power

Question 3

Transformer windings

winding - 12000 w = 12 000 ohms x 1 A

winding - 12000 w = 120 V x 100 A

Question 4

Operating Principles of Transformers

Transformers and any other electromagnetic devices. Need the ____. (Affected).

VA = AC power (But inductive and capacitance Current (A)

Answer 4

ratings

Question 5

Transformers principles

____ - changing ___ of one conductor creates ___ for neighbor conductor

Answer 5

Mutual induction

current, voltage

Question 6

Transformers - don’t need magnetic core or electrical conductive connector. (Inefficient though)

Question 7

Primary winding - coming ___

Secondary winding - coming ___

Secondary winding is connected to ___

Answer 7

in, out

load

Question 8

Primary turn / secondary turn = turn ratio

True or false

and is inversely proportional

Answer 8

True

Question 9

Step up transformers - to convert to ___

Step down transformer - convert to ___

Answer 9

bigger, smaller

Question 10

Air core (no core)

inductor (not transformer) - no second core (coil)

Question 11

Impedance - AC resistance (ohms) (inductance & capacitance)

Ep / Es = Ip / Is

E = volts
I = current

p = primary
s = secondary

Ep / Es = Np / Ns

Volt and turn = must be equal

Question 12

Bigger volt winding. More insulation (thinner) - polarity

windings:

series - 240 v
parallel 120 v

Question 13

core

permeability up, retentivity down, hysteresis down

Question 14

adjacent - subtractive
diagonal - additive

Question 15

Ratings

KVA - how much that transformer can transform
total KVA - all transformers in that case

Question 16

HV - max voltage without breaking insulation

If there is a lower voltage in secondary winding - connected parallel

Applied voltage is higher - series (-+)

Autotransformers - do have conductive link (cheaper to build, small voltage change) (limited use, less copper)
-used for multiple power sources

Question 17

Standard dual winding - no conductive link
Auto transformers (voltage divider)

Step up - secondary big, primary small
Step down- Primary big, secondary small

Question 18

Variable autotransformers - variat, powerstat (donut shape, knob) - moving wiper, changes turn ratio.