Electrical Question: Electrical Spikes trip main Circuit Breaker

[archeye]

This is for sure off PC topic, but I (a bit ) trust the people in this forum

I have a Hob on a 3 phase supply. 2 single ovens below each supplied from 2 different phases.

One oven now trips the panel main circuit breaker when switched to include the lower heating element.

I took the oven out to investigate and with it plugged into a wall socket it all works fine.

I disconnect the lower element, connect back to the 3 phase supply and it still trips the breaker.

So it is in the electronics. I assume a capacitor is probably no longer doing its job.

Summary:
With the oven plugged in the wall it works fine so I consider the 3 phase circuit breaker does not attenuate spikes but the single CB for the wall sockets does.
I did think to reconnect the lower heater and put a 250v CB (EU Type B) inline with the cooker live and neutral wires (both are switched in my system) but I do not have one spare Type B.
I do have however have a spare one that is meant for motors (EU type C)

Experimenting with electrics is dangerous so I am looking to build my knowledge before moving forward.

So QU. I have found what is going wrong and would an inline type C CB work.

Just I am not knowledgeable enough about the CB's.
Note: I completely rewired the whole house and CB boxes so I know what is there.

 

[PowerEngineer]

Well, what you describe sounds like much more than a normal home kitchen setup -- especially having three-phase power. If I understand you correctly, you have the hob (cook top?) and the two ovens wired up in a delta configuration (each between two phases), and you are tripping the three-phase breaker?

Be aware that breakers are just glorified on/off switches that have the ability to automatically trip when certain conditions are met. Breakers do nothing to attenuate voltage or current spikes (other than open). Breaker current ratings are generally set to the steady state load current they can handle. Breakers are meant to trip if they sense a sustained current level much higher than their rated current, but are also designed to ignore higher transient spikes in current caused when devices are first energized (known as inrush current). As the resistance of heating elements starts out low and then increases as they heat up, it could be that your breaker isn't handling the current spike very well.

It is also possible that your three-phase breaker may be designed to trip if it senses an imbalance in the currents among the three phases (somewhat like GFI protection on single-phase circuits), and the loads you have wired up are certainly going to be imbalanced.

It might make better sense to have individual breakers for each of the three devices.

Please bear in mind that I have only a sketchy understanding of your wiring -- and know nothing about the electrical codes that apply where you are (or even where you are). Your best bet is to enlist the help of a licensed electrician.