Circuit breaker tripping but not EL

[Andrew_van_Zyl]

Commercial building in Strydom Park JHB that'd had several sparks doing stuff over many years.

Intermittent 20A CB on socket circuit tripping usually after loadshedding. Earth Leakage doesn't trip.

Offending CB swopped out for new. Same thing.

Installed monitoring device on the circuit to see increased amperage and/or warrage. My thinking the trip is caused by amps exceeding CB, or, in the case of low voltage just after loadshedding, an increase in Watts.

Not picking anything up that should cause a trip.

As I understand it a CB will trip on excessive amps or a hard short hot to neutral or ground. Or an arc.

My thinking (and advice needed pls):-
1) Unplug everything.
2) Test each socket with ELCB tester
3) Megger each circuit
4) Test every appliance çonnected to sockets

Thoughts?

Thanks in advance

Sent from my SM-A226B using Tapatalk

[Isetech]

Replace the breaker with a D or Curve 1 breaker, do look impedance tests at the socket outlets to verify the circuit are correct.

Fit those those ellies fridge protectors on appliance which you suspect could have high inrush currents. it would be cheaper than doing power quality tests. I normally charge R10 000 just to take the fluke 435 out the case.

if it still trips then get a PQA and set it to transients/inrush and switch off/on.

Commercial building in Strydom Park JHB that'd had several sparks doing stuff over many years.

Intermittent 20A CB on socket circuit tripping usually after loadshedding. Earth Leakage doesn't trip.

Offending CB swopped out for new. Same thing.

Installed monitoring device on the circuit to see increased amperage and/or warrage. My thinking the trip is caused by amps exceeding CB, or, in the case of low voltage just after loadshedding, an increase in Watts.

Not picking anything up that should cause a trip.

As I understand it a CB will trip on excessive amps or a hard short hot to neutral or ground. Or an arc.

My thinking (and advice needed pls):-
1) Unplug everything.
2) Test each socket with ELCB tester
3) Megger each circuit
4) Test every appliance çonnected to sockets

Thoughts?

Thanks in advance

Sent from my SM-A226B using Tapatalk

[Justloadit]

It could be that the specific circuit powers up equipment which has rectifiers and smoothing capacitors.
Check what type of equipment is connected on this circuit. VSD drives, Inverter aircons, etc.
During load shedding, the respective capacitors completely discharge, then at the end of load shedding, when the power comes back, the high inrush current as all the capacitors charge up, will cause the circuit breaker to trip.
When you switch the breaker off then on again this does not trip as the time may be too short to discharge the capacitors completely as per a load shed cycle.
Most equipment that has this type of issue has a built in in rush current controller, however this may have failed and hence what you are experiencing.

[Tang]

Hi, I would think that after load shedding the diversity factor is out the window and any mcb might tripp including main mcb.

Sent from my R1PLUS_1 using Tapatalk