Attach Cords equipment to connect 230 V single phase

Question 1

What is the voltage and frequency of single phase power generation in Australia

Answer 1

230 V
50 Hz (Pass through +ve and -ve cycle 50 times each sec )

Question 2

What is the equivalent d.c value of a.c .

Answer 2

70.7% of the peak a.c value

Question 3

What is the basic arrangement of an electrical circuit ?

Answer 3

Question 4

What are the names of the following protection device symbols ?

Answer 4

Fuse
Circuit breaker

Question 5

List the name, operating principle and advantages of the following protection devices.

Answer 5

Question 6

List the name, operating principle and advantages of the following protection devices.

Answer 6

Question 7

How does Residual Current Devices (RCDs) work ?

Answer 7

RCD detect an imbalance in the active and neutral currents in a circuit.

An imbalance occurs when ‘leakage’ current flows in the protective earthing conductor, causing the active and neutral currents to be unequal.

The RCD detects the unbalanced currents and ‘trips’ to switch off the current in the circuit.

Question 8

How do resistance testers work ?

Answer 8

Ohmmeter leads connected across component

Ohmmeter apply small voltage across component and read current

Resistance is calculated and displayed.

Question 9

What equipment is this and how does it work ?

Answer 9

An insulation resistance tester applies a d.c. voltage (250 V, 500 V or 1 kV) across two conductors that are insulated from one another.

Low resistance reading = insulation cannot contain or hold the test voltage

High reading (MΩ) = insulation is in good working order.

Question 10

What is Parallax Error ?

Answer 10

Question 11

live and earthed parts of an electrical installation, or parts thereof, including consumers mains and submains shall be not less than _____ ?

Answer 11

1 M Ohm

Question 12

When testing insulation resistance, the rule of thumb is to select a test voltage that is at least _______ ?

Answer 12

Double the normal operating voltage that the insulation will be exposed to.

Question 13

Label the pins.

Answer 13

Question 14

What does the test result indicate ?

Answer 14

Question 15

What does the test result indicate ?

Answer 15

Question 16

Fill in the blanks

Answer 16

Question 17

Fill in the blanks

Answer 17

Question 18

List the colour code

Answer 18

Question 19

What is International Protection (IP rating) ?

Answer 19

Rating system classifies enclosed equipment based on the degree of protection provided against the ingress of solid objects (e.g. dust) and water.

dust = 0 to 6
water = 0 to 8

Question 20

What are the main functions of earthing system ?

Answer 20

Ensures stability of the supply voltage.

Ensures that protection devices function correctly.

Eliminates the chance of hazardous voltages appearing between exposed conductive parts.

Question 21

What is the meaning of this symbol ?

Answer 21

Class II Equipment
Double insulated

Question 22

Define the following types of insulation

Answer 22

• Sup = in case basic fails
• Doub = to create redundancy

Question 23

What is a short circuit ?

Answer 23

Question 24

Why is 250 V used for insulation testing on equipment containing surge protection device.

Answer 24

High voltage can cause a low resistance from active to earth via the surge protection device

Question 25

State the min insulation resistance btw live and earth conductive parts for the ff:

Class I appliances:

Class II appliances:

Appliances containing mineral insulated metal sheath heating elements:

Answer 25

1 MΩ
1 MΩ
0.01 MΩ

Question 26

It is essential that insulation resistance testing is only carried out on equipment that is _____.

Answer 26

disconnected from the supply