New build... Confusing ssr issues

[eric_pwb]

Hi all,

I am finally done building my new all electric RIMS system and have just started testing the system. It is brew troller controlled.

I am having a major issue with me SSRs. In my build I have three, one two switch a 110v duplex I use to drive my single pump, a second one to switch one leg of a 240v element for the rims and a third to switch one leg of the 240v element for the kettle. All of the relays are switching the same leg. The issue is the relay will switch the circuit for the 110v pump fine, but the there is constantly 240v at my sockets for the elements. I have triple checked all of my wiring and nothing is crossed and everything is where it should be. To rule out bad ssr failed in the "on" position I swapped the two causing issues to the pump circuit and they function as expected, except for after having been connected to the 240v circuit, on power connection to the panel the relay would energize the circuit for about a second before shutting off and working as expected. I also checked for issues with my switching current by disconnecting the 12v and the ground entirely and the issue still persists. My outlets show no continuity between any of the terminals. It is my understanding that there is no need to have a ssr relay on both legs of the 240v circuit as the unswitched leg will just remain hot.


Any suggestions or help would be much appreciated, as I am pulling my hair out trying to figure this out.

 

[ChuckO]

When there is no input signal and no load on an SSR you will see the line voltage on the output. As soon as you plug in the heating element you should see the voltage drop to zero.

I'll bet that you have the pump plugged in and are looking at the voltage on the other side of the duplex outlet. Unplug the pump and then measure the outlet. You will probably have 120v there.

 

[Walker]

right... there is leakage current ion an SSR. It's always there when the SSR is 'off'. A meter will give you very strange readings if you have no load connected to the output of the SSR because of that leakage current.

 

[eric_pwb]

When there is no input signal and no load on an SSR you will see the line voltage on the output. As soon as you plug in the heating element you should see the voltage drop to zero.

I'll bet that you have the pump plugged in and are looking at the voltage on the other side of the duplex outlet. Unplug the pump and then measure the outlet. You will probably have 120v there.

right... there is leakage current ion an SSR. It's always there when the SSR is 'off'. A meter will give you very strange readings if you have no load connected to the output of the SSR because of that leakage current.

Thanks guys! That explains half of my conundrum, that explained the weird readings I was getting before.

BUT... now that I was confident in my panel wiring and setup I started running a wet test. During the test I started experiencing another related issue, that I was able to confirm with my multimeter. When the load (element) was attached to the relay and none of the relays were triggered there was no current draw on any of the circuits. But when the brewtroller would trigger the relay for the pump, the circuit for the element would close as well without the brewtroller closing the control side of the relay, when this would happen I would see about a 16a draw on the "hot" side of the relay, and the diagnostic led on the relay would not light.

After much frustration, I calmed down had a few homebrews and traced it back to faulty transistor array on the brewtroller. When it would trigger the pump relay it would leak enough current to trigger the element relay, but not enough to light the diagnostic LED. I swapped it with one of the others on the board and the problem disappeared!!

I would not have thought to look there without your help, I had no idea that without a load a SSR leaked. Thanks Guys!

 

[missing link]

my pumps will occasionally hum when the SSR is off. Must be from the same leakage issue. Is there anyway to stop this?

Linc

 

[Walker]

The leakage current is minuscule. Miliamps or less.

It should not make your pump do anything.

 

[eric_pwb]

The leakage current is minuscule. Miliamps or less.

It should not make your pump do anything.

Mine do nothing, and if there is no load I see current, but with a load none.

 

[EarthBound]

Because I bought used SSRs, I tested them as soon as I bought them. In order to test them, they must have a load. I used a 9VDC wall wort and a lamp to test them.

 

[Walker]

Mine do nothing, and if there is no load I see current, but with a load none.

The leakage current is still there when you have a load connected. Its just so tiny it doesn't do anything.