I'm trying to find a solid-state solution for switching a mains supply on and off. That's it. No phase control, just on and off.

I assumed I would be able to buy an opto-triac, where all you have to do is turn on its LED and hey presto, you have a high-current solid-state switch. But while lots of manaufactuers make opto-triac drivers (so you have to add an extra triac), I can't find any such thing as a plain-jane opto-triac for power applications (a couple of amps at 240Vrms, say).

Solid-state relays (opto-MOSFETs) don't seem to have enough current cabability to handle mains applications reliably either.

What am I missing? Do such things not exist?? I'm not talking hair-raising power levels here, just a couple of amps would be ample!

 

For that kind of current they need to have some size due to power dissipation. If they are to small in size they will overheat. Even a Triac will need some kind of cooling finn for that kind of voltage/current combination

 

a Zero Crossing Opto Coupler (like MOC3042) can be used for triggering a BTA series Thyristor like shown. An Optocoupler is only an interface and cannot handle more than a few millamps.

Ramesh

 

I see- that's the impression I was starting to get. Thanks!

 

Complete assemblies are available; google "solid state relay." There are also some kits available, which may come up in your search.

 

http://www.jameco.com/1/1/449-kd20c40ax-dc-ac-solid-state-relay-control-voltage-4-32vdc.html

The link show a page for a 40 amps ac solidstate relay.

Cheers

Alberto

 

I'm trying to find a solid-state solution for switching a mains supply on and off. That's it. No phase control, just on and off.

I assumed I would be able to buy an opto-triac, where all you have to do is turn on its LED and hey presto, you have a high-current solid-state switch. But while lots of manaufactuers make opto-triac drivers (so you have to add an extra triac), I can't find any such thing as a plain-jane opto-triac for power applications (a couple of amps at 240Vrms, say).

Solid-state relays (opto-MOSFETs) don't seem to have enough current cabability to handle mains applications reliably either.

What am I missing? Do such things not exist?? I'm not talking hair-raising power levels here, just a couple of amps would be ample!

there are quite a few solid state relays out there, probably you are not looking in the right places.

 

I can't find any such thing as a plain-jane opto-triac for power applications (a couple of amps at 240Vrms, say).

Solid-state relays (opto-MOSFETs) don't seem to have enough current cabability to handle mains applications reliably either.

What am I missing?

Here in N.A. the Opto22 range cover it, not sure if available in the U.K. however?
Max.