3 phase heater problem

[Flakey]

Hi there,

I have a number of 22kw heater sunning of 3 phase supply. There is a dial with 4 settings 1 being the lowest output 4 the highest.
The problem I have is when ever it is set to maximum output it is knocking out the breakers not discriminating at the rcd but knocking out the main breaker as we'll. When I have opened the unit 1 pf the connections to one of the heating elements has burnt out. It has happened to a couple of other units too.
Could it be it do with the system not being adequately balanced?

Any help would be greatly appreciated.

James

 

[Marvo]

The burned connections are more likely down to poor terminations than balance. The tripping fault could be balance related or it could just be plain old fashioned overload. You're going to need a sparky with some test equipment to establish the circuit loading etc.

 

[polo1]

What value/type are the breakers?