Has anyone ever done a teardown of a solid state relay like this?


Is it anything other than a triac on a heatsink in a glorified package?

 

It typically also has an opto-isolator IC to isolate the input signal from the AC and generates a zero-crossing turn-on gate signal to the Triac to minimize high current transients and EMI.

 

And doing a teardown would probably leave you as much in doubt as to what's in there as before you started.

 

Have a look at page 5 of the datasheet.

 

Have a look at page 5 of the datasheet.

Do you mean page 3?

 

I see it on P5.
Max.

 

The picture was generic (I just grabbed it off eBay). I was just curious about what was inside the block diagrams. Looking at the datasheet you guys pointed to, it says that the rated current is for a resistive load, but the current for an incandescent light (also a resistive load) can only be 25% of the rated current.

 

Tungsten filaments have very low resistance when cold, and thus very high inrush currents. Apparently, the SSR will not tolerate those inrush currents even for a very short time.

 

It can tolerate them fine for a few turn-on cycles, and maybe even a few dozen or a few hundred cycles. But these things are rated for hundreds of thousands of cycles, and all of those little jolts add up.

ak

 

That sort of ssr is usually built using two SCR's connected back to back (and not a triac, so as to make them more reliable), and triggered using an opto isolator.

But as has already been said, I doubt you'll be able to discern anything if you try to pry them open... you'd only see a mess since they're completely encapsulated in hard resin.

 

I see it on P5.
Max.

Ah, I see it now. I didn't see the page numbers at the edges (I only looked at the bottom) so I was referring to it as being on the third page of a five page document. But the pages ARE numbered, they are just numbered, 3, 4, 5, 28, and 29.

 

The picture was generic (I just grabbed it off eBay). I was just curious about what was inside the block diagrams. Looking at the datasheet you guys pointed to, it says that the rated current is for a resistive load, but the current for an incandescent light (also a resistive load) can only be 25% of the rated current.

Where does it say that the current for a resistive load can only be 25% of the rated current?

It says that the rated current is FOR a resistive load. For an incandescent light you need 4x the nominal current of the light.

 

Where does it say that the current for a resistive load can only be 25% of the rated current?

It says that the rated current is FOR a resistive load. For an incandescent light you need 4x the nominal current of the light.

Or were you just pointing out that an incandescent light is also a resistive load?

Yes and no. As others pointed out, it's a resistive load whose resistance at turn-on is a lot lower than the nominal resistance when on. Hence the necessary derating.

 

Where does it say that the current for a resistive load can only be 25% of the rated current?

It says that the rated current is FOR a resistive load. For an incandescent light you need 4x the nominal current of the light.

Isn't 1/4 equal to 25%?

 

Where does it say that the current for a resistive load can only be 25% of the rated current?

I did some quick math to get 25%! And that was for an incandescent load, not a resistive load (but an incandescent load is a resistive load - kinda). If you could ramp the voltage to an incandescent load, you might be okay, but since these are only ON of OFF, the inrush current would eventually kill them.

 

All the ones I have used, Opto22 etc have a current rating of X10 rated for 1 cycle.
Max.