N-E bond
On power failure, my Contactor gives me E-N bond. All good. (islanding mode). However upon re energising, the grid side rcd trips out. The E-N release needs to happen milliseconds before powering up. How can I achieve this please. Any ideas ?. Thank you .
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I had this same re-coonection trip on an installation with a front end RCD because it is a TT earth connection. Took us AGES to find out what was going on. In short - the whole consumer unit Earth leakage in the house is approx 20mA. The inverter has a 7mA leakage [i'm trying to find out from technical why ....] when the Inverter 'switches on' which is approx 60secs after GRID power & THE SAME TIME as the N-E relay de-energises. SO it seems that it is the N-E is causing the trip....... It's not! Its because 20mA + 7mA exceeds the trip threshold of a 30mA RCD! Because in my system the GRID supply RCD can 'see' both the Consumer Unit and the Inverter.
So this is what you need to 'fix' depending on your wiring configuration.
But I would offer that:
1) You need the L-E connection for Island mode but not in GRID mode so you need a relay not permenant connection! SA advise permenant connection for integrity BUT I am not sure it's allowed in UK.
2) Ideally, the Inverter needs RCD protection.
3) Make sure your RCDs are the new Type A [for AC and DC loads]