The EC Fan keeps tripping the RCD

[Mark_Djorn]

Hi All,

Weird matter happening here and I hope you can help!

My 3 Pahse EC Fan is connected to a sensor and a controller for the temperature setpoint. A control panel to manage the EC Fan is in the room. EC Fan above faux ceiling. The panel has it's own MCB. The RCD is upstream, before the maintenance isolator upstream the panel.
So, inside the panel: MCB.
Outside the panel upstream: isolator.
upstream the isolator, in a separate room: RCD.

Everytime I switch off the isolator to the panel, the upstream RCD (from the other room to the panel) trips.

Based on the EC Fan contractor, I must increase my RCD sensitivity from 100mA to 300mA to solve the issue. Also, it seems the problem is the panel.

Based on Panel contractor, the panel is fine. The problem is the EC Fan.

As a matter of fact, after an initial investigation, it seems that when I open my isolator, there is a "weird" returning path to neutral. What I mean is: I open the isolator, measure between L1 upstream the isolator and the Neutral downstream the open isolator and fine 240V. I thought it was merely induced. But when a load is connected to those wires, the lights is ON. Clearly it's a ligit path.

Based on my electrician, that returning path to Neutral should not exist, even with an EC Fan. How comes that my EC Fan comes with a Neutral wire that is solidly connected to ground? Why my.RCD trips only when switched OFF and not during operation as well?

Thank you in advance All.
Mark

 

[perwoo47]

i think that is fault in isolator.
when isolator is opened, it seems that phase line and grounded neutral line are in contact.
so, i think RCD was triped beacuse detected leakege current.

 

[Mark_Djorn]

i think that is fault in isolator.
when isolator is opened, it seems that phase line and grounded neutral line are in contact.
so, i think RCD was triped beacuse detected leakege current.

Thanks for your reply and good guess. I tried that by totally disconnecting the cables from the isolator. The weirdest thing is that I still measure 240V between upstream the isolator and the totally disconnected neutral from downstream. Not sure why