Solid State Relays, Optoisolators VS Optocouplers

[danny davis]

At work we use different kinds of Solid state relays
What happens a lot of the solid state relays get their output is either shorted or open

What causes a solid state relays output to get shorted or open?

Some solid state relays are Opto-isolator Triac or some use Opto-isolators with Mosfets

I'm not sure what is shorting or opening the Triac or the Mosfets inside the solid state relays which is the output of the solid sate relays

Plus I'm not really use what the difference is between an Optocoupler VS an Optoisolator?

But what's inside a Solid state relay is an Opto Triac

 

[KerimF]

In general, the output of a solid state relay could be:
(1) a triac (or bi-thyristor) for AC load.
(2) a MOSFET or bipolar transistor for DC load.

Usually a triac, thyristor or bipolar transistor could be turned on by a current supplied to the gate or base (in case of MOSFET, by a voltage).
In optoisolator ICs (may be called optocoupler), the input current produces an internal light beam that, in turn, stimulates the internal opto gate or base.

 

[danny davis]

In general, the output of a solid state relay could be:
(1) a triac (or bi-thyristor) for AC load.
(2) a MOSFET or bipolar transistor for DC load.

Yes true, But what is causing the Solid states relays output to BLOW a SHORT or OPEN on it's output? it will Blow the Triac or Mosfet, what causes this to happen? OVER LOADING IT and what else?

 

[KerimF]

I see now. You meant faulty optoisolator ICs having an output shorted or opened always even if they are driven properly.

I am afraid that your question is general. So I can say the causes, for these faults to happen, are much like the ones that damage conventional triacs, Mosfets and transitors (not opto).

By specifying a circuit (also the main components it uses) and how it is supposed to work, it would be possible seeing the possible cause or causes for its failure.