Inverter Fail-Over relay circuit

[Jester]

This is a AC transfer relay circuit that transfers from 120V MAINS to battery backed 120V inverter when the MAINS fail.



Do you think it will be safe and reliable?

Please delete

[Zero999]

No. You need a fullwave rectifier and a smoothing capacitor, to stop the relay from turning on and off at 60Hz or trying to.

I Googled the EE2-24NU.
https://www.mouser.co.uk/datasheet/2/212/KEM_R7002_EC2_EE2-1104574.pdf

Assuming I've got the correct data sheet, the coil resistance is 2k88, so you need a 12k 1W resistor.

I think this is a penny wise, pound poor solution and it would be better to use a 120VAC relay, even if it's more expensive and through hole.

[tecman]

Another issue is the 00 uf capacitor on the relay coil.  This will delay the relay drop-out time resulting is a delay before the inverter power is applied.  Also the capacitor will cause a slow release which could cause some additional arcing as the contacts switch.  Minimize the capacitor sizing by using a full wave rectifier and only enough C to eliminate buzzing.

paul