Failed SSR

So it happened to me

The last two brews my PID has been over shooting set temps by a few degrees and I could'nt figure out why.

I needed to replace a switch so I took the opportunity to rewire my indicator light to the output of the SSR so I would have a visual indicator of when the element was firing, so that I could wait till it was'nt, to flick said switch.

Anyways, I get that wired in and turn on the control panel and the light lights. Change set value to below process value and the light remains on, although dimmer this time.

Get out the volt meter and come to find that I have 32 volts on the cord.

I guess that my SSR has failed partially closed
What do you guys think?

I think you are measuring the values without a load wired into the SSR output. If that is the case, all bets are off in trying to measure anything.

Just saying.

What p-j said. When i measure the voltage of my ssr output without a load i get 120v. When i put a load on it i dont get leakage.

Thanks I will check that now

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This is where a "wiggy" style meter is worth its weight in gold. It has a built in solenoid to present a load to the circuit. Modern digital multimeters do not have enough input impedance to load the relay. In the electrical classes I teach, this is one of the first things we discuss when we talk about meters.

Im sorry guys, but Im not picking up what your throwing down

If I connect the load to the plug I will have no place to take a reading
Are you saying that the SSR will allow voltage to pass through it when it is not being told to be closed by the PID?

Exactly. It will appear that the SSR is in a "closed" position until a load is put on the circuit. Take the voltage reading at the output terminal opposite of the line voltage supplied.

so should'nt it show the full 120 volts not just 32 with or without load

Also, isn't your PID telling you exactly when your element is firing? It has a light, it blinks...what are you firing the SSR from, control-wise? My Auber PID has a nice light that coincide's with the SSR firing.

But yeah voltage measuring through an SSR is whack jack. Fully closed I get full voltage. Don't bother. Use a "does my element turn on and heat properly" measure, instead.

But really I wouldn't bother putting in a light to tell you when your SSR is firing or not, if you need that then mount the SSR in such a way that it's visible.

It has a plastic case on it and a light on it for this reason, no?

I was just hoping to have a light that would be easier to see is all
But I guess its not going to happen

redman67 said:

I was just hoping to have a light that would be easier to see is all
But I guess its not going to happen

Click to expand...

But doesn't your PID give you this light? Mine does, aren't they all pretty much the same? The duty light or whatever, bottom left. Lights whenever it sends voltage to the SSR.

Yea but I wanted something easier to see

P-J said:

I think you are measuring the values without a load wired into the SSR output. If that is the case, all bets are off in trying to measure anything.

Just saying.

Click to expand...

To back up P-J, SSRs switch current, not voltage.

Your light switch turns voltage on & off.

But SSRs are more like a stove top eye control with two settings - full on & very, very low. So low that when your element is connected and the SSR is turned "off" you will measure little or no voltage across the element.

But disconnect the element and you will read a voltage - how much depends in how "off" the SSR really is and your meter's input resistance. Also, there is definitely enough voltage past a "off" SSR to shock you!

I can back up everyone here. I had similar issues when I wired mine and was doing a final wire check. Crazy voltages across my SSR. Couldn't figure it out for the life of me. Upon the sage advice of my eBrew brethren, I connected the element and everything worked as it should. Measure across the SSR terminals when the element is wired in and you should be golden.

Thanks all I would not have guessed that