Circuit Breaker Types

What is the BS number for a circuit breaker

• BS 3871

• BSEN 60898

• BSEN 61009

• B2 88

What types on circuit breakers are there?

• Types 1,2,3,4

• Types 1,2,3

• Types A,B,F

• Type B,C,D

What are the trip curves multipliers for circuit breakers Types B,C and D to BSEN 60898

• x1, x2, x10

• x 5, x 6, x 7

• x5, x10, x20

• x 10, x20, x 30

If you have a 6 ampere circuit breaker type B, what will be the maximum trip current from that circuit breaker?

• 30 amps

• 32 amps

• 60 amps

• 120 amps

What is a start up surge?

• A current rising rapidly after switch on

• A current dropping after a rapid start up.

• A current remaining steady during start up

• A voltage rapidly rising during start up

What are the design times for circuit breaker tripping?

• 0.2 second for final circuits and 5 seconds for distribution circuits

• 5 seconds for final circuits and 12 seconds for distribution circuits

• 0.1 second for final circuits and 4 seconds for distribution circuits

• 0.4 for final circuits and 5 seconds for distribution circuits

Where could you find a Zs value?

• IET Wiring Regulations

• Code of practice for building

• NICEIC

• NAPIT

Why do we have to alter the Wiring Regulations earth loop impedance values

• As they are wrong

• They need adjusting for maximum earth loop values

• The cables are operating at maximum temperature, adjusted for room temperature.

• The cables could have a worse resistance value

What is the formula for Zs

• Ze + R1 + R2

• R1+ R2

• Zs + ( R1+R2)

• Ze+(R1+R2)

Why do we often put motor on a Type C circuit breaker?

• Because of the high start up currents

• Because of the low start up currents

• Because of the high start up voltages

• Because of the low start up voltages