2 SSR's blew up on me last night

hope this helps?

 

The confusion here is that the NKK S821 switch does not use terminals 1 and 4 as is stated in the data sheet here:

http://www.nkkswitches.com/pdf/stoggleshighcap.pdf

If you look at how the switch operates in that data sheet you will see that it is in fact a DPST switch. This diagram is very specifically designed for that switch. 1 and 4 are off in this diagram

Edit to further clarify: The S821 doesn't have terminals 1 and 4 so it has a 'none' position and an off position.

 

When I looked up the specs of the switches you have, I don't see anything that says they won't work. The problem you may have run into is if you used the pin numbers indicated on the diagram to wire them.

So the datasheet for your switch.

http://www.nkkswitches.com/pdf/stogglesmedhighcap.pdf

Find on page A104 (3rd page) your switch S331R. This tells me the specs of your switch @250V it will take 25A. I don't think you are exceeding that with your elements.

It also shows what terminals are paired together.

It shows 1-3 and 4-6 are pairs. The diagram (your drawing in the first post) however shows 5-6 and 2-3 as pairs for switch. Now it should only have 4 terminals so I don't know how you wired the switch. It is possible that something got messed up here. Where I am confused is that you were mentioning contacts 2 and 5 above. The datasheet clearly states that the S331R doesn't have terminals 2 and 5. The only terminals should be in the 4 corners of the switch.

Based on the datasheet. It should be wired like this

Hot -> SSR -> SSR -> 1 -> 3 -> Panel Light -> Plug -> Element -> Plug -> 6 -> 4 -> other leg of hot.

I would verify this with an ohm meter though.

All this is based on where you said the manufacturer part number is S331R. If you actually have a different switch all bets are off. Sometimes they mess up things when they ship them out. Look for a part number on the switch.

 

If that is how it is wired, I think that is what is wrong. Based on what I am reading from the data sheet your diagram you posted doesn't match what I am reading. Do you have a meter with an Ohms setting that you can use to verify the pinout of the switch. The way I read your diagram and interpret the datasheet, if you kept the wires where they are in the digram, rotate the switch 90 degrees. Well I should say the numbers. The lines of the switch are oriented right. The terminal numbers don't match what I am reading.

So if it is wired like you show the data sheet says pin 4 and 6 are a pair so when the power was on you sent power from pin 4 (power from SSR) to pin 6 (other hot terminal strip) which would have been a short which in theory means that the only load on the circut is what minimal resistance is in the SSR and would likely burn it up. Kind of like what you saw happen.

I have to say I am trying to diagnose this from MN which is pretty hard to do over the internet. It would explain the fried SSR. I would think it would have blown the fuse right away off the top of my head. This may have not been the case because the SSR wasn't the only load on your diagram. You are pulling some load because you are pulling 110V off one of the legs for powering your PIDs. Also to be honest, I haven't worked with SSRs personally yet. My parts are on the way. While I have worked with contactors and relays which in theory operate in a very similar way, there may be some differences with a SSR which may explain the delay before tripping the relay.

 

According to what you saying about wiring then yes I have it wired wrong for sure.


switch by Ludahchris, on Flickr


switch by Ludahchris, on Flickr

 

I see what your saying now

 

Ok. Pics help. Ignore the 2 and 5 in your terminal numbers. They mold the plastic backing with the numbers and drill it out for the terminals used in the application. So where you are saying 1/2 and 4/5 it really is 1 and 4.

Again check with an ohm meter but I would bet that you need to swap the red wire on 4 with the black wire on 3.

Then you will have red on 1-3 and black on 4-6 like I mentioned.

This is assuming your wire colors match what your diagram is. The way it is explained in the data sheet it appears you have shorted it out like I mentioned in the last post.

Either way you have SSRs that need to be replaced. You may have to replace the switches as well. Those contacts are rated to 25A. When shorted they would have potentially seen whatever Amp rating your breaker is. Was it 30A? you can burn the contacts. I know I keep saying this. Get an ohm meter on the switch. Not only verify the pinouts of the contacts that they match what I am reading in the datasheet but also compare resistance. It might show if the contacts are burned a little inside the switch. One side of the switch has never seen any current and the other side probably saw more than what it is rated for. If the resistance is different between the sides, I would replace the toggle switches.

 

Red and black are both hot legs white is neutral and green is ground. My gfci is 30a and hopefully with all the problems I didnt harm that. I'll check the switches tomorrow when I get home from work and I am still learning how to use the meter so hopefully I can figure that out as well.

 

Yeah, this explains the blown SSRs. The only thing I can't explain for sure is that I would have thought that the breaker would have tripped right away. I just haven't worked with SSRs like that to know how they behave.

Actually as I am typing this I am thinking it over.... What was the PID set to when you turned things on? If they were set to manual where it was pulsing. You were shorting but PIDs are set up to do PWM (Pulse Width Modulation) so they pulse the power on/off. So depending on the rate of the pulse it may have taken a moment or two before the SSR heated up enough to fail. Some solid state devices fail open others fail closed. It might have taken a bit for it to fail short. The breaker may also not have been able to react quick enough. You do have a GFCI breaker right? They are usually more sensitive to things but for the GFCI part they watch voltage going out vs voltage coming back. If there is a difference in miliamps they will trip assuming the current is leaking where it isn't supposed to.

This all could very well explain everything you saw. The blown SSRs, the delay trip of the breaker.

Odds are your PIDs are fine. For damage you are likely lucky in that odds are it will be limited to the SSRs and possibly the switches. As long as you don't have any burned wires.

 

Ok, normal colors which is good.

Get things fixed and test out the breaker. Odds are that will be fine.

On the meter the ohms setting is the setting that looks like this.



Set it to that and touch the probes together to see what it looks like when it sees a complete circuit. I have a few meters but most of mine say OL (Open Loop) when they are not touching and the resistance when they are. You will want to disconnect all the wires when checking resistance and functionality of the switch. The shorted SSR and other stuff may throw off your readings if you leave the wires connected.

Hope this all helps and glad no one was hurt.

 

I'll leave you my phone number in PM - Always good to meet fellow brewers!