MCCB Types

[Franklymdear]

Can anyone help me understand the difference between types A, B, C, D etc MCCB/MCB? Reference to the relevant EN would be useful.

Thanks

 

[Blackcountryman]

Franklymdear,

I think you are refering to tripping curves. Standard is BS EN 60898, it think I don't have books at home to check and the memory is not what it was.

A breaker with a B curve has a magnetic trip 3 to 5 times Rated current (In) and is typically used in domestic type installations

Type C mag trip is 5 to 10 times In.
Type D mag tip 10 to 14 times In.

To select the correct breaker you need to know the inrush when the load is energised. Typicaly a motor will be 6 times Full load current.

You also get catorgory A & B breakers, this is defined in BS EN60947-2 and refers to tripping delay provided. This nornally refers to Moulded case circuit breakers (MCCB) rather than MCB.

Hope this helps