rcd tripping

[oxford 12]

Just been called to a tripping problem in a lab,where 3 seperate rcds would trip out for no reason.After some time discovered a heat damaged neutral connection in a seperate db in another part of the building.With this connection repaired ,the tripping problem ceased.Can any one explain this .:dizzy2:

 

[malcolmsanford]

commoned neutral, was this system feed by an isolating transformer?

 

[rich.250]

Was it after the rcd's??
And is there discrimination between and in series?

 

[rich.250]

Sorry- Any*