Backup automatic transfer switch

[David B.]

So I'm running a hybrid converter connected to a 100amp 220v sub panel. I'm powering a/c feeds right now that are 6000watts. So the sub panel has grid power if needed for 100 amps for future expansions of solar.
So if the hybrid convertor fails for any rare condition I would like to use the 100 amp grid service that's available. To achieve this I need a ATS that will trip on when the hybrid fails if it ever does. Trouble is all I'm finding are generator type ATS's or Chinese with no ul listing. So how do I find a 100amp 220v ATS. For loss of feed power from the hybrid convertor. I'm not talking loss of solar or batteries, I'm talking catastrophic failure of the convertor it's self. I know it's rare but eventually inevitable when I'm gone from the house. Yes I could use a 50amp ATS but I'm wired for 100amps so might as well use it.

 

[Hedges]

I want the same, a reliable deadman switch that will transfer from "UPS" inverter output to straight on grid, in the event inverter shuts down.

A relay powered by inverter would of course have the function, but doesn't have a wide enough contact gap to be an "isolator". Also some people say loads like refrigerator need an "off" time before connecting out of phase (but I'm not sure I believe that for small motors.) I envision a knife switch, worked by weight or spring, held in other position by an air cylinder.

I look forward to what people may identify.

 

[David B.]

Hedges, actually I am quite surprised at the lack of response. I guess there may not be a good solution.

 

[kommando]

The ones I have seen are of Chinese origin, youtube disassembly video's show the internal wiring for the main electrical flow is the same regardless of the Amp rating so not going near my house. So sticking to a manual German made 3 pole 3 position (Grid/Off/Generator) 100A switch. At least it ensures there is always a gap in the power supply, only the central heating controller and the internet router seem to object and need some buttons pressed. The Chinese auto ones all seem to be 230V single or 3 phase and no provision for US split phase.

 

[Hedges]

Yes, but you've now bumped the thread back to top of "What's new", during daytime. While some of us are having coffee.

My concern is freezers powered through Sunny Island. I have had them trip offline due to things like paralleled breakers that had aged and high PV production. A smaller simpler setup could be more reliable.

We could probably build something, with time delays etc. The most robust devices are probably thermal time delay relays, would want the heater powered by grid not inverter.

An "Isolator" has 1" gap between contacts; circuit breakers provide that, while supplementary protectors do not. Relays tend to have a pretty small gap. Could be inverters get away with relays by checking for open before picking up load from battery. Or just have testing for UL listing rather than meeting the definition of isolator.

You could build what you want from mechanical or solid state relay, although I want very robust isolation between inverter output and grid, both for lineman safety and to protect my equipment.

These double-pole double-throw safety switches contain two linked knife switches. I imagine something like that with weight or spring to pull it one way (grid), air cylinder with normally-open solenoid valve and air or vacuum pump powered by inverter to pull other way.

Siemens General Duty Double Throw 200 Amp 240-Volt 2-Pole Outdoor Non-Fusible Safety Switch DTGNF224NR - The Home Depot

Double Throw switches are intended to transfer loads from 1 power source to another. All 2 and 3-pole double throw switches are suitable for use as service equipment including non-fusible versions when

www.homedepot.com

The ones I have seen are of Chinese origin, youtube disassembly video's show the internal wiring for the main electrical flow is the same regardless of the Amp rating so not going near my house. So sticking to a manual German made 3 pole 3 position (Grid/Off/Generator) 100A switch. At least it ensures there is always a gap in the power supply, only the central heating controller and the internet router seem to object and need some buttons pressed.

Would they serve to auto-transfer to grid when inverter down? Got a link?

 

[kommando]

Yes, but you've now bumped the thread back to top of "What's new", during daytime. While some of us are having coffee.

My concern is freezers powered through Sunny Island. I have had them trip offline due to things like paralleled breakers that had aged and high PV production. A smaller simpler setup could be more reliable.

We could probably build something, with time delays etc. The most robust devices are probably thermal time delay relays, would want the heater powered by grid not inverter.

An "Isolator" has 1" gap between contacts; circuit breakers provide that, while supplementary protectors do not. Relays tend to have a pretty small gap. Could be inverters get away with relays by checking for open before picking up load from battery. Or just have testing for UL listing rather than meeting the definition of isolator.

You could build what you want from mechanical or solid state relay, although I want very robust isolation between inverter output and grid, both for lineman safety and to protect my equipment.

These double-pole double-throw safety switches contain two linked knife switches. I imagine something like that with weight or spring to pull it one way (grid), air cylinder with normally-open solenoid valve and air or vacuum pump powered by inverter to pull other way.

Siemens General Duty Double Throw 200 Amp 240-Volt 2-Pole Outdoor Non-Fusible Safety Switch DTGNF224NR - The Home Depot

Double Throw switches are intended to transfer loads from 1 power source to another. All 2 and 3-pole double throw switches are suitable for use as service equipment including non-fusible versions when

www.homedepot.com

View attachment 182456




Would they serve to auto-transfer to grid when inverter down? Got a link?

This is a disassembly video but not the one that showed the load wires are unchanged with the amp rating.

Here is the one that shows the load wires cannot be 100A capable

Of course you could add proper wiring.

A typical Amazon UK listing

https://www.amazon.co.uk/Automatic-Generator-Changeover-Millisecond-Switching/dp/B0C6RK2VLN/ref=sr_1_35?crid=1PRT26920OXR7&keywords=auto+changeover+switch&qid=1702405452&sprefix=auto+changer%2Caps%2C94&sr=8-35