3 pole minature circuit breakers

[controlman]

Can someone remind me
Is a type 2 breaker = to a type B
Can't find my file
Many Thanks

 

[Guest123]

No, the maximum fault loop values are lower for old 3871 type 2's than newer 60898 B's.

 

[controlman]

Lenny
That would possibly explain the problem- are the starting characteristics similar eg Type B, 3 times, C, 7to 10 times
Been to look at an old control panel. 3 of the type 2 rated 25amp breakers were defective (very unusual!)
Been informed a "sparky" was holding then in whilst starting the motors.
My line of attack- obtain Flc of motors- check cables and sizes- and rate and size breakers for type C (motor rated with infrequent starts- if many starts type D)

 

[thepurple1]

A type D breaker should not be fitted with a motor, only fit a type C. The overloadand contactor fitted on the motor should only do 6 starts an hour, if more starts are reqired fit an inverter. more expensive but its the right way

 

[Guest123]

A type D breaker should not be fitted with a motor, only fit a type C. The overloadand contactor fitted on the motor should only do 6 starts an hour, if more starts are reqired fit an inverter. more expensive but its the right way

Agreed.

 

[controlman]

Why do Merlin Gerin and every other manufacturer give a table in their catalogues for motor starters
showing the recommended MCB IN TYPE H, TYPE C & TYPE D
eg
4kW 5.5HP 3 phase c 20amp d 16amp
Are you saying the manufacturers are wrong or do you have a reason. Is it to do with the let through energy, in that case you have to size the contactors to suit.Or
Is it the type of co-ordination (where things are allowed to be damaged to a certain degree ) under a fault condion.
The parts then have to be replaced