I need a switch that's switches from primary power to secondary if primary shuts off....

[Inventer82]

I'm trying to divert power from a load if main power goes out then switches to an alternet power source. That should be the easy part, here's the catch... if main power turns back on I'd like the switch to detect the voltage and automatically switch back to the the main power while breaking the circut of the secondary power source without any back feeding. Does that make sense?? I have a basic understanding of electronics but I'm trying to step my skills up. Thanks maybe some feedback will help. Is this something already made?

 

[Bluejets]

Sounds like an auto transfer switch for solar or a generator.

Problem is, any solar system must be arranged to stand down in the event of power failure.
Reason being , the line workers do not want any solar supply being pumped back down the line when they shut it down for maintenance.
You can argue back and forth the possibility of circumventing this but the supply authorities will have no part of it.

As for generators, any standby system must be installed by an approved lecky and certified by the supply authority.

 

[duke37]

Seems like a changeover relay with the coil connected to the main supply would do. When this fails, the relay will drop out and the power can be taken from the auxilliary supply.

 

[Bluejets]

Seems like a changeover relay with the coil connected to the main supply would do. When this fails, the relay will drop out and the power can be taken from the auxilliary supply.

Gets more involved than that.
To begin with there needs to be set delays to ensure power is either removed or returned for a given length of time.
Then it needs dual contactors both mechanically and electrically interlocked.
Exception to the latter is smart control devices costing big bucks and again certified and approved.

 

[duke37]

There is no indication that it is anything to do with the mains, If it is an emergency generator then the changeover needs approval.
It could be a 12V supply for a model railway or a 24V supply for railway station slave clocks. As is often the case, we are kept in the dark, particularly if rhere is no emergency changeover.

 

[Bluejets]

I'm trying to divert power from a load if main power goes out

There is no indication that it is anything to do with the mains,

Does to me.

 

[Col. Panek]

How big a load and how much money do you want to spend on this? A manual generator switch would be the cheapest way. Or you can get a lockout mechanism that lets you use the current house input breaker or a generator breaker, but not both.