How many relays (split phase)

[Robbert]

Hi, I would like to isolate my inverter from AC-in, and only allow AC-in if that is neccesary.
The reasons why I want this are:
1) the inverters that I use, use AC power if connected to the grid. If disconnected they use from the battery/solar
2) we have a very instable grid and after outages we see high peak voltages that could be harmfull for connected appliances

I bought two relays that I want to connect. In order to stop power in I can use just one relay on one leg.
That means that the other leg still has 110v going in.

Especially with regards to point two (disconnect from grid because of peak voltages), is it smart to add a relay to both legs?

I added a picture of the test setup (with two relays). Don't mind the colour of the cables since this is just a test on my desk.

 

[timselectric]

All ungrounded conductors are supposed to be controlled by a common operator.
Which means that you should be using a two pole relay/contactor. (Not two individual relays)

 

[Hedges]

Well, that would certain be true for a transfer switch.
Simply as a disconnect, consider how fuses operate.

How would his inverter behave if it saw power on L1 but not L2?

 

[timselectric]

Well, that would certain be true for a transfer switch.
Simply as a disconnect, consider how fuses operate.

This is a disconnect (its purpose is to turn off the circuit) , not a fuse.

How would his inverter behave if it saw power on L1 but not L2?

No idea,
It could open its own input relay. (Hopefully)
Or just throw an error and continue sending one leg through.

 

[timselectric]

One way around it.
If the inverter will open its own input relay, upon loss of one leg.
You could get away with controling only one leg. If the relay is installed inside of the inverter enclosure. (Maybe In the wiring compartment)

 

[Robbert]

All ungrounded conductors are supposed to be controlled by a common operator.
Which means that you should be using a two pole relay/contactor. (Not two individual relays)

Thanks for your feedback. I'll start searching for a 2 pole din relay