3-fase SSR connection

1

Hi,

I am finally building the HERMS installation that I have been designing and gathering parts for.

It has 2 3-fase SSR’s (20A version mounted on DIN Rail heatsinks).

I am now so far that I tried if they were working, so connected everything as I thougt was correct, set 5V on the right SSR (in the picture top), light went on that it was switching, so everything OK.

Went to the left SSR (in the picture bottom) and did the same thing, one loud BANG and the power went off :stuck_out_tongue: Black (burned) wires on L1 and L2 on the incoming side.

Have been measuring the SSR, and phase 1 and 2 have now no resistance anymore, while on the other (still working SSR) there is resistance, so I think that the SSR is broken.

I have ordered an other one from brewpi (These were also from brewPi) but want to make sure that I connected everything correctly:

A1 → L1 incoming
B1 → L2 incoming
C1 → L3 incoming

A2 → L1 outgoing
B2 → L2 outgoing
C2 → L3 outgoing

Input minus → V-
Input plus → V+ (5v)

I know that there are two brown wires, but could not get gray wire. so the ones with the gray label on them are supposed to be gray :slight_smile:

Strange thing is that the other SSR is connected exactly the same way and that works.

There was no load on the output side, just the outlets (3 fase power outlet). Am I doing something wrong or was this a bad SSR (it can happen right?)

Measured everything before turning it on, there were no shorts.

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Thanks for confirming before I order a new one and break that one too…

2

A1 → L1 incoming
B1 → L2 incoming
C1 → L3 incoming

A2 → L1 outgoing
B2 → L2 outgoing
C2 → L3 outgoing

Input minus → V-
Input plus → V+ (5v)

That’s correct. It does sound like a defective SSR I think. I don’t see your input+ in the photo. How did you connect the 5V? From the same supply as the minus?

3

Thanks Elco :slight_smile:

Indeed the input+ was from the same supply as the minus, just did that with a loose wire that I put between the power supply and the ssr to bypass the brewpi and make sure that everything was working before frying the brewpi :wink:

I connected the 24V minus and the 5V minus together to get a shared minus reference (needed for the pumps as I understood in an other thread here on the forum). If I measure the 24V+ to - and 5V+ to minus the values are spot on, so I don’t think that is the problem?

4

Sounds like you did everything correctly.

5

Thanks! Then it is waiting for the new SSR’s to arrive (ordered two, just to be sure…), I saw you shipped them yesterday, but postNL has to process it still. :slight_smile: