Help please.

[Marvo]

I have a problem with an MCB circuit breaker, I was too embarrassed to ask in the main forums because the others might laugh so I thought I'd ask here.

The thing I'm unsure about is my MCB has a lot of letters and numbers stamped on it and I've got no idea what they mean. Maybe the trainees can copy/past the list below and add a description next to each one to explain what they all mean.


In : 20A
Curve : C
CAT : A
Icn : 6000 (M6)
415 V AC
Ui : 500 V
Ue : 460v
Uimp : 6 kV
I2t classification: 3
RH : 95 % at 55 °C
O-C : 20 000

 

[Simonslimline]

I have a problem with an MCB circuit breaker, I was too embarrassed to ask in the main forums because the others might laugh so I thought I'd ask here.

The thing I'm unsure about is my MCB has a lot of letters and numbers stamped on it and I've got no idea what they mean. Maybe the trainees can copy/past the list below and add a description next to each one to explain what they all mean.


In : 20A - rated current or current setting of protective device.
Curve : C - instantaneous trripping current ( between 5 & 10 x In)
CAT : A - overvoltage category
Icn : 6000 (M6) - Maximum fault current the breaker can safely interrupt without blowing to bits. (replace after such event occurs)
415 V AC - ​voltage rating
Ui : 500 V - Rated insulation voltage
Ue : 460v - continuous operating voltage
Uimp : 6 kv - rated impulse withstand voltage
I2t classification: 3 - energy let through value of device.
RH : 95 % at 55 °C
O-C : 20 000

Not so sure about the others. My college notes don't go in to that much detail unfortunately. Hopefully one of the other members can help

 

[Marvo]

Thanks Simon, great start. Hopefully others will chip in with a few suggestions for the rest of them.

 

[happysteve]

RH is relative humidity. O-C sounds like a rated number of open/closed cycles.

 

[Marvo]

Spot on Steve, both of those are correct.

 

[Simonslimline]

I have edited my first post to include the others.

 

[Richard Burns]

I did not know what CAT A was!

 

[Marvo]

I have edited my first post to include the others.

Looks like I'll have to think of a more difficult question next time. Between you and Steve it's a wrap on this one.

I wouldn't worry Richard, it's a more obscure classification and every day is a school day after all

 

[happysteve]

Thanks, Andy, good question Made me think a bit, and I've learnt summat.

 

[Paul.M]

Just to add to the question:-

Icn : 6000 (M6) - Maximum fault current the breaker can safely interrupt without blowing to bits. (replace after such event occurs)

Q. My MCB has a box with a number 3 in it after the Icn 6000 (M6). What does it mean???

 

[Simonslimline]

Just to add to the question:-

Icn : 6000 (M6) - Maximum fault current the breaker can safely interrupt without blowing to bits. (replace after such event occurs)

Q. My MCB has a box with a number 3 in it after the Icn 6000 (M6). What does it mean???

Ics - The maximum fault current the device can interrupt safely without loss of performance.