Hi,

Can anyone suggest where I can get a normally closed contactor with a 220v coil?

This is to try fix my neutral/earth bond behaviour on my hybrid inverter.  I’ll connect the normally closed contacts between N and E on the output of the inverter, and then connect the coil to the grid side.

Result is with grid power present the contactor is open and we don’t bond the output.  If the grid power goes then the contactor goes to the normally closed position and the output is bonded.

Its not absolutely 100% since there can be out of spec power on the grid enough to pull in the contactor but the inverter will island and the neutral with float.  But it is much better than the all or nothing I have now.

Anyway - where can I find such a contactor - 1P normally closed 220v coil.  I guess the power rating needn’t be much - 32A would be plenty.

Thanks,
Steve

 

Well, there appears to be several multi-configuration contactors at RS components. Of course those do more than you need, but as long as they have one suitably rated NC contact you're home free I'd think. Prices start around R350 it seems, not bad I'd say.

I sourced these relays from AC/DC for use with my sonofs. Not sure if applicable of suitable to your application, but depending on which connector you use 1-2 or 2-3 they can be connected to be either normally open or normally closed.

The two red wires at the bottom are going onto the 220v relay coil. 

As long as it is rated for the full fault current (aka the breaker on the input side and/or the short circuit current of the inverter), then Bob's your uncle.

Here's what I did, thanks to a kind forum member who had a recycled contactor for me. 

It would be nice to show you it working but my upload is limited to 3MB.

Anyway - this is to deal with the floating neutral when the inverter islands, but without introducing a 2nd NE bond when the inverter is grid-tied. 

The coil of the contactor is powered from the grid - output of the 2P breaker on the left.  The NC contacts bridge neutral and earth from the inverter and before that E/L trip on the right. 

Effect is that when the grid is present contactor pulls in and no NE bond here.  We have only the one at the council connection point. When the grid dies the contactor releases and the bond is made. 

Yes, there are corner cases where there is a brown out and the inverter islands but there is still enough volts to hold the contactor in.  But its much better than before. 

Yes, cack-handed cutting of the DB cover was required to fit the contactor.