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jakenbake 08-04-2012 10:51 PM

SSR problems
 
I've been lurking around here for quite a while now, and I rarely post. I decided to go to electric brewing. I am having problems getting the SSR to switch (at least I think...)

My setup is a basic as it gets:
240VAC in
Auber PID controller powered of 240VAC
Fotek SSR-60DA SSR
L6-30R plugs and single receptical
5500W heating elements

The plan is to have only the HLT or BK plugged in at a time and do a tiered batch sparge.

Anyway, the problem is that when I load the SSR, I am getting the full 240VAC dropped across it. When I unload the SSR (unplug the heating element) and the output is open, the SSR is dropping about 80mVAC across it. So it is obviously working correctly with no load and not working with a load. Is the SSR junk? Or am I missing something?

I can whip up a diagram real quick in visio if it will help explain my setup.

Jake

edit: I should also note I'm an electrical engineer, and that is why this pisses me off even more... :D

wottaguy 08-04-2012 10:56 PM

a visio dwg would be very helpful at this point as long as it reflects the actual way you have it wired now.

Quote:

Originally Posted by jakenbake (Post 4305541)
I've been lurking around here for quite a while now, and I rarely post. I decided to go to electric brewing. I am having problems getting the SSR to switch (at least I think...)

My setup is a basic as it gets:
240VAC in
Auber PID controller powered of 240VAC
Fotek SSR-60DA SSR
L6-30R plugs and single receptical
5500W heating elements

The plan is to have only the HLT or BK plugged in at a time and do a tiered batch sparge.

Anyway, the problem is that when I load the SSR, I am getting the full 240VAC dropped across it. When I unload the SSR (unplug the heating element) and the output is open, the SSR is dropping about 80mVAC across it. So it is obviously working correctly with no load and not working with a load. Is the SSR junk? Or am I missing something?

I can whip up a diagram real quick in visio if it will help explain my setup.

Jake

edit: I should also note I'm an electrical engineer, and that is why this pisses me off even more... :D


jakenbake 08-04-2012 11:20 PM

1 Attachment(s)
As requested (note, no neutral coming over, just 2 hots and an earth ground, on a 30A breaker):

SleepyCreekBrews 08-05-2012 01:42 AM

that looks correct to me ....have you tried tripping the SSR with a 9v battery?
(my fotek 40 had an LED indicating it's on, does yours?)

jakenbake 08-05-2012 02:29 AM

Yep, LED flashes on/off.

I can see the 12V from the PID toggling at the correct duty cycle with a volt meter.
I'll try a 9V battery and see what happens.

edit:9V battery gives same result. bad SSR maybe?

Junkster 08-05-2012 03:00 AM

It sounds like you got a dud SSR. Have you tried it with a smaller load (like a couple of 50W light bulbs in series) instead of the element to see what happens?

jkarp 08-05-2012 12:33 PM

What are you reading the voltage with, a multimeter? You do realize SSRs are a current switch, right? There's always some leakage - a few mA. More than enough for a decent multimeter to read the voltage, which is essentially always present. Test your SSR with a real load, like light bulbs in series just as Junkster suggested.

jakenbake 08-05-2012 12:40 PM

I will give the light bulbs a try. The leakage would explain it working under no load. Still doesn't explain why I see all the voltage dropped across the SSR and not the heating element when the led on the SSR is lit up, right?

jkarp 08-05-2012 01:58 PM

Quote:

Originally Posted by jakenbake (Post 4306356)
Still doesn't explain why I see all the voltage dropped across the SSR and not the heating element when the led on the SSR is lit up, right?

I don't understand what you're saying here. If the SSR light is on, one would expect to see voltage and the load is allowed to draw the current it requires.

SSRs can be a bit unintuitive. Best to think of them as a current switch. The 240V voltage is always present, regardless of the input signal (SSR light). When the input signal is low (SSR light off), the SSR is essentially a constant current source of a few mA @ 240V. Testing the open output terminals of an SSR with a high impedance device like a multimeter is also very problematic. Most SSRs must see an actual load before they will operate correctly.

jakenbake 08-05-2012 02:42 PM

I'm not taking my volt meter between the output and return, I'm taking it across the SSR and across the heating element.

The more I think about it, the more I am thinking the SSR is bad. When I have no load attached to the output of the SSR, the voltage dropped across the SSR is in the mV. Thats b/c the leakage. Once I hook it up to the load (heating element in this case) I'm dropping all 240V across the SSR, and only mV across the load (again, the mV across the load is b/c of the leakage).

I'll order a replacement SSR. Thanks for the replies.


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