Dead Ssr

[fraser_john]

Had my system set up for a 5am start, should have been able to come out at 7am and find the mash sitting at 76c, HLT sitting at 77c. Instead the HLT is at 20c. Fark what is wrong. Open up the control case, all indicators on the HLT show its recieving 12v dc, check the voltage across the high voltate side, 235v. Dammit.

Had to wait until the mash had reached mash out, shut the whole thing down, rush job replacing dead SSR with a spare one I had (talk about lucky).

Got the system back up and mash is holding at 76c whilst the HLT catches up. So much for an early start.

What is the cause of SSR failure? I have had this for over 8 years without a hassle, yet all of a sudden, with no human interaction, it dies? Worked perfectly last weekend on the weizen.

 

[Mitternacht Brauer]

Had my system set up for a 5am start, should have been able to come out at 7am and find the mash sitting at 76c, HLT sitting at 77c. Instead the HLT is at 20c. Fark what is wrong. Open up the control case, all indicators on the HLT show its recieving 12v dc, check the voltage across the high voltate side, 235v. Dammit.

Had to wait until the mash had reached mash out, shut the whole thing down, rush job replacing dead SSR with a spare one I had (talk about lucky).

Got the system back up and mash is holding at 76c whilst the HLT catches up. So much for an early start.

What is the cause of SSR failure? I have had this for over 8 years without a hassle, yet all of a sudden, with no human interaction, it dies? Worked perfectly last weekend on the weizen.

Hi John,
It is my experience that SSR's can die for any number of reasons . Temperature variations over time ,a short on the output. I have seen them look perfectly normal but not work and I have seen some let go where only the back Ali plate and the terminals were left behind. It would be my guess that your unit may have only died from old age.If you were able to change the SSR and continue normally then the rest of your system must be OK .

Always have spares handy

 

[Sammus]

How is the SSR rated? They get damn hot close to their rated max. I've used to use a 40A SSR switching a 1200W (5A) element in an espresso machine and that absolutely cooked even bolted to the steel chassis of the machine. I reckon a few years of that would kill it for sure. Maybe look into some higher rated SSRs and some good heatsinking too?

 

[Mitternacht Brauer]

I agree with Sammus and I see you have the two of there on Heat sinks .Do you have heat transfer paste between the SSR and the heatsink?

 

[fraser_john]

It was rated at 40A and drawing just under 19A, mounted on a decent heatsink, I had used thermal paste on the back of it whilst mounting as well.

Originally my system was designed so that it was always on, even whilst the mash heater element was activated. Recently with the addition of the control case to my system, it is now controlled by a PID, with a normally closed relay between the mash SSR and the HLT SSR. This gives electric priority to the mash electrics. So compared to my early system, the SSR gets switched a whole lot more, may have failed because of this change in use.

 

[browndog]

I think the SSR didn't like you mashing at 76C FJ ! Sorry about the OT, but what kind of beer do you mash at 76C ?

cheers

Browndog

 

[kirem]

I think the SSR didn't like you mashing at 76C FJ ! Sorry about the OT, but what kind of beer do you mash at 76C ?

cheers

Browndog

If I may speak for FJ, mashout temperature

 

[technocat]

I have been using these from Virtual Village on ebay and run them at 2400W they are bolted direct to the inside of a PVC cabinet and they only run warm and never hot.

View attachment 35185

If the ambient temperature is high in their enviroment then more adequate heat sinking would be required. Junction temperatures for the mosfets in a SSR are typically rated at 175C Trouble is that when these temperatures approach or exceed these temps, resistance in the device increases causing thermal runaway and thus destroying the device. This is the bane of all transistor devices. If a SSR is rated at 40 amps and only half of that rating is being drawn then it is operating well below it rated specification and if it fails it is obviously being made to pass a hell of a lot more current that it is supposed to. A circuit breaker in the domestic enviroment would save the day one would think, four inch nails in fuse boxes excluded. If a 40 amp SSR is running unusually hot say on a 15 amp circuit it should be replaced as it is in my view faulty.

:icon_cheers:

 

[kirem]

I have been using these from Virtual Village on ebay

View attachment 35185

do you know if they are zero crossing? it doesn't list it in the specs?

 

[browndog]

If I may speak for FJ, mashout temperature

Yes, obvious now that I reread the post.

 

[technocat]

do you know if they are zero crossing? it doesn't list it in the specs?

Kirem, if you mean do they latch yes they do.

BN

 

[kirem]

Kirem, if you mean do they latch yes they do.

BN

latching so the SSR waits until the source voltage crosses zero to turn off, to help reduce EMI

 

[technocat]

no zero cross to reduce EMI

Not sure what you mean or do mean switching transients. From what I can remember of zero crossing in my days at TAFE electronic trades a long time ago Zero crossing in SSR's were to switch and latch a triac on at the zero point of the supply thus not needing continuous DC at the input of the opto coupler. This was an energy saver.
Some SSR's although silent are notorious for producing electrical hash as do their mechanical cousins

BN

 

[kirem]

Not sure what you mean or do mean switching transients. From what I can remember of zero crossing in my days at TAFE electronic trades a long time ago Zero crossing in SSR's were to switch and latch a triac on at the zero point of the supply thus not needing continuous DC at the input of the opto coupler. This was an energy saver.

Cheers
BN

zero crossing;
View attachment 35206

non-zerocrossing or random;
View attachment 35207

zero crossing significantly reduces EMI, random switching will induce or produce EMI and back EMF etc etc.

I'll just email and ask the supplier

 

[technocat]

zero crossing;
View attachment 35206

non-zerocrossing or random;
View attachment 35207

zero crossing significantly reduces EMI, random switching will induce or produce EMI and back EMF etc etc.

I'll just email and ask the supplier

Yeah OK I see the spike on the waveform why is this a problem for you

 

[Gout]

i gather switching at zero ( no current) is kind on the SSR.

does this prolong life or is it purely for EMF?

 

[kirem]

Yeah OK I see the spike on the waveform why is this a problem for you

yeah I don't and most people don't like EMF interference it upsets the missus, the neighbours, the kids etc, infact I think it may now be against the law.

It is no biggy, it is normal a specification that is pretty clearly stated on a SSR spec sheet, I'll just ask the supplier.

I need some new SSRs and those from virtual village are a bit cheaper than auberins. Auberins are zero crossing and I just wanted to compare apples with apples.

i gather switching at zero ( no current) is kind on the SSR.

does this prolong life or is it purely for EMF?

at a guess, I would say both

 

[technocat]

To my mind EMI (electro magnetic interference) is a none advent. My computer would probably put out more EMI than a standard SSR. I agree that around sensitive equipment EMI must be kept to a minimum. Any equipment with oscillatory circuits contained therein usually contain snubber circuits to keep hash to a minimum, often to comply with legal standards set by the DOC. However for the homebrewer I would hardly think it relevant.

Cheers
BN

As an after thought while I am brewing I usually have the radio on in my workshop. I have it tuned in to the ABC AM (amplitude modulation) mainly because I live rural and Hobart FM (frequency modulation) reception is shithouse down here. Now AM is highly susceptible to EMI because of the very nature of its transmission characteristics and I can honestly say I get no EMI on the radio whatsoever.

Cheers
BN

 

[kirem]

To my mind EMI (electro magnetic interference) is a none advent. My computer would probably put out more EMI than a standard SSR. I agree that around sensitive equipment EMI must be kept to a minimum. Any equipment with oscillatory circuits contained therein usually contain snubber circuits to keep hash to a minimum, often to comply with legal standards set by the DOC. However for the homebrewer I would hardly think it relevant.

Cheers
BN

I disagree, it is relevant for me.

I run a PID enhanced temperature controller, the noise from a random switching SSR is enough to induce noise onto the thermocouple signal lines, I can filter the noise, but it slows the response down significantly.

 

[technocat]

I disagree, it is relevant for me.

I run a PID enhanced temperature controller, the noise from a random switching SSR is enough to induce noise onto the thermocouple signal lines, I can filter the noise, but it slows the response down significantly.

Then if it is a problem I suggest you buy your SSR's from a distributor who can give you a detailed spec sheet and pay top dollar for the privilege. Virtual Village as AFAIK is a UK marketing operation of over supply stock with little info on what it sells other than what the manufacturer may come up with. This is merely an observation nothing more nothing less.

BN