Just seeking a wee bit of clarification on I delta m. Literature indicates that it is the maximum breaking capacity of residual current as distinct from the maximum breaking current. Just not sure how to interpret that.
Just seeking a wee bit of clarification on I delta m. Literature indicates that it is the maximum breaking capacity of residual current as distinct from the maximum breaking current. Just not sure how to interpret that.
On an RCD the only thing it breaks on in is a current difference.
On an MCB the only thing it breaks on in is total current.
But an RCBO and perhaps some clever programmable breaker design, really has two mechanisms for operating the contacts, and maybe these operate at different speeds, so the time for contacts to be damaged (burnt) is different.
Now we may have two different Im maximum fault currents to do the same damage as the contact heating and arc damage is all about I squared R *time...
In those cases when its not obvious what we meant, we need to distinguish the 'Im' s for the 2 kinds of fault and this is one way to do it.
And then to totally muddy the water, if it is installed after a 100A death or glory fuse (to further limit the time/ energy ), then the it is conditionally rated to 10kA.
Mike.