Melted 40Amp FOTEK SSR

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mosstradamus

mosstradamus

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Before I built my 50 Amp e-HERMS panel, I spent a lot of time looking at designs that were posted on this sight, particularly PJs. I thought using circuit breakers within the panel, as well as contactors, was a little overkill....but based on what I was already spending, decided to keep them in the design.

I bought 40Amp FOTEK SSRs and didn't initially have a problem. After a couple of batches, I set my temp for the strike water at the beginning of my brew day, and then went about my normal preps. I returned to find that I had blown through the temperature and my strike water was 185 degrees. I used the contactor to kill power to the element, added some cold water to reach my strike temp and then re-energized the circuit. The BCS 462 maintained temperature for the rest of the day...without runaway temps.

On subsequent brew days, I continued to have the same problem. I verified that the 5V DC input from the BCS was appropriate, but the SSR was sticking open during the initial heating of strike water in my BK or getting my HLT to initial mash temp. If I killed the circuit with the contactor, the SSR would reset and didn't stick when energized for small temperature changes or maintaining HERMS temps.

I changed out the 40Amp FOTEK with another 40Amp FOTEK. I had good results for 3 brew days, and then started to experience the same symptoms. I hadn't gotten around to ordering new SSRs from Auber, and figured I could live with the sticky SSRs for a little while. With all the other projects I have going on...a little while turned into 6 months.

2 weeks ago, I was heating strike water in the BK and getting my HERMS water in the HLT up to temps at the same time. After 20 minutes of heating, the circuit breaker for the HLT popped. I looked inside, could smell something hot, but didn't see a problem. I continued the brew day, resetting both SSRs when the initial temperatures were reached and didn't have any further problems.

The next day, without the rush to get things done, I could see a little deformation of the HLT SSR. If I had seen it when I popped the CB, I would have called it a day.

My 40 Amp FOTEK running my fermentation chamber hasn't had any problems at all. I am making an assumption that the lower volts and amps aren't great enough to make the SSR stick....at least not yet.

3 out of 3 40Amp FOTEK SSRs installed on 25Amp circuits experienced sticking while bringing strike and heat exchange water up to initial temps.

A big fan of contactors and multiple circuit breakers in the panel....they have already paid for themselves.

Not a big fan of FOTEK.........I just switched to Auber.

Fotek1.JPG


Fotek2.JPG
 
my educated guess would be that something is amiss with either your wiring or your element..... I have had no issues myself with my fotec/mypin ssr's with 25 brews or so on them.
For you to have two that failed the same way and one to get so hot it melts I would think there is too much resistance or load somewhere.
Your not really providing much info about what kind of enviroment these are being used in.
How hot was your heat sink getting? what kind of ventilation does the heatsink have?
What gauge wire are you running and what is the wattage of your element?
 
- 5500w HLT
- 4500w BK
- 8ga to the CB
- 10ga from the CB
- 8 or 10ga to the elements(I was able to get a deal on 8ga)
- 25amp CB
- SSRs are wired between CB and Contactors
- SSRs are mounted to external heat sinks with thermal grease
- Heat sinks are warm, but not hot
- The CB has only tripped once (as indicated in the above post)
- Everytime I significantly overshot the temp setpoint, I observed the element actively heating with the SSR input indicator light extinguished. The light would be illuminated prior to reaching the setpoint.
- The system has worked perfectly since I installed the new Auber SSRs.
- All the wiring has intact insulation, all the connections are tight, there is no evidence of arcing, and the connections all look "fresh"....the wire looks new.

Based on the performance of the system since the replacements of the SSRs, I don't see anything amiss. I would be very interested in suggestions on what else to check.
 
I hadn't thought to check that......the SSRs are mounted with the heatsinks to the enclosure. I have a good ground at the chassis, and the mounting method is the same as it was previously. It was not loose when I took the old SSRs out.
 
The other thing to check for is if the controller has an open collector output or a level output. Open collector outputs can float and cause 1. The MOSFET in the SSR to not close once current is running and 2. Once it "turns off" the voltage can float and cause the resistance of the MOSFET to change thereby creating extra heat.

Edit: depending on the technology it might be called "open drain."
 
mosstradamus said:
- 5500w HLT
- 4500w BK
- 8ga to the CB
- 10ga from the CB
- 8 or 10ga to the elements(I was able to get a deal on 8ga)
- 25amp CB
- SSRs are wired between CB and Contactors
- SSRs are mounted to external heat sinks with thermal grease
- Heat sinks are warm, but not hot
- The CB has only tripped once (as indicated in the above post)
- Everytime I significantly overshot the temp setpoint, I observed the element actively heating with the SSR input indicator light extinguished. The light would be illuminated prior to reaching the setpoint.
- The system has worked perfectly since I installed the new Auber SSRs.
- All the wiring has intact insulation, all the connections are tight, there is no evidence of arcing, and the connections all look "fresh"....the wire looks new.

Based on the performance of the system since the replacements of the SSRs, I don't see anything amiss. I would be very interested in suggestions on what else to check.
Click to expand...
I'm all for sharing experiences but you "just" switched to auber ssr's according to your posts? A little quick to be making assumptions dont you think?

the odd thing is you say the light goes out on the ssr when its stuck on... I may be wrong but I was under the assumption the light normally stays on when these stick in the on position...

I myself have the ssr wire after the contractor (I used 25A relys for my 4500w elements) otherwise my ssrs would always be working as long as my control panel had power regardless of whether the element is switched on with the relay or not... and this would cause it to be on for long periods of time trying to obtain a temp that it would never reach because the rlay is preventing the power from reaching the element.

(I wired my two relays on a single three position switch so only one relay/ssr/element gets power at a time because I only have a 30a circuit.)
 
I would check what your circuit is actually drawing using a clamp on amp meter. It's also worth noting that SSRs probably use nothing more sophisticated than a triac for switching, and triacs have a reputation for sticking on at times.
Consider running a regular contactor with an SSR instead of using the SSR for switching the high current load. I've used just triacs and resistors with good success, and for pennies compared to SSRs.


H.W.
 
Owly055 said:
I would check what your circuit is actually drawing using a clamp on amp meter. It's also worth noting that SSRs probably use nothing more sophisticated than a triac for switching, and triacs have a reputation for sticking on at times.
Consider running a regular contactor with an SSR instead of using the SSR for switching the high current load. I've used just triacs and resistors with good success, and for pennies compared to SSRs.


H.W.
Click to expand...
I've read that ssr's use mosfets for switching the power on and off and this is one of the reasons they leak voltage....
some of the machinery I service uses triacs and while they do stick they usually work well. (they also dont switch on and off anywhere near as quickly and as often as they do when controlled by a pid in a brew configuration.)
 
augiedoggy said:
I've read that ssr's use mosfets for switching the power on and off and this is one of the reasons they leak voltage....
some of the machinery I service uses triacs and while they do stick they usually work well. (they also dont switch on and off anywhere near as quickly and as often as they do when controlled by a pid in a brew configuration.)
Click to expand...

Some of the old CNC stuff that I used to service with DC servo motors used SCR's that switched dozens of times per second to feed a DC motor. A Triac is just two SCR's back to back so that it will work with AC, so I'd assume a Triac could switch pretty quick too.

DC Servo motors went by the way in the early 90's in favor of AC Servo's - which are glorified three phase stepper motors, an the SCR's were replaced by transistors I assume, although the early 90's were about the end of component troubleshooting.
 
atoughram said:
Some of the old CNC stuff that I used to service with DC servo motors used SCR's that switched dozens of times per second to feed a DC motor. A Triac is just two SCR's back to back so that it will work with AC, so I'd assume a Triac could switch pretty quick too.

DC Servo motors went by the way in the early 90's in favor of AC Servo's - which are glorified three phase stepper motors, an the SCR's were replaced by transistors I assume, although the early 90's were about the end of component troubleshooting.
Click to expand...

Funny you say that, some of thew uv flatbed machines Ive recently started to service share the same frame and drive systems as a cnc machine.
 
augiedoggy said:
I'm all for sharing experiences but you "just" switched to auber ssr's according to your posts? A little quick to be making assumptions dont you think?

QUOTE]

An assumption is accepting something as true without any proof...I made the assumption that I fixed it before I even powered it up. Every successful use moves me further away from assumption.

I don't think I am the first person to use a PJ design, but I haven't seen a lot of folks with the same issue.

I "just" have 2 full cycles under my belt...how many more cycles do you think I need to have before I can declare victory?...its a long way to 6 sigma.
Click to expand...
 
mosstradamus said:
augiedoggy said:
I'm all for sharing experiences but you "just" switched to auber ssr's according to your posts? A little quick to be making assumptions dont you think?

QUOTE]

An assumption is accepting something as true without any proof...I made the assumption that I fixed it before I even powered it up. Every successful use moves me further away from assumption.

I don't think I am the first person to use a PJ design, but I haven't seen a lot of folks with the same issue.

I "just" have 2 full cycles under my belt...how many more cycles do you think I need to have before I can declare victory?...its a long way to 6 sigma.
Click to expand...
Your first post said everything was fine with the foteks for "the first few couple of brews" too... All I'm saying is it seems you are being quick to blame the failures on the foteks and being just as hasty in thinking the new ones fixed your problem and are not going to fail.. A lot of members here are very quick to blame these particular failures on inexpensive ssrs only to find the same results after shelling out more money for the ones auber sells same thing with the cheaper pids... (truth is that more people who dont spring for the expensive pids are also less likely bother to research the correct way to wire and operate them) I here people claim they have gone through three or 4 and others state they have used the same couple for years with no issue and it kind of makes a person wonder.. if it were one then yeah Id say its defective but with each additional failure the odds of that go down.

I have been told that due to the design of these ssr's the longer they remain "on" without switching off the hotter they get... that may or may not be true I honestly dont know but from what I know of how mosfet switching works it makes sense.
Click to expand...
 
This SSR has a TRIAC output not a MOSFET. I looked up the datasheet. TRIACs are nice since they only turn off at the zero crossing of the sine wave. This prevents spikes or inductive kickback from damaging them. If you're having luck with the new relay then by all means keep with it. If it eventually fails then maybe think about an electro-mechanical relay. I think too many people get caught up in 'new' electronics and forget about the reliable past. Solid state relays are great for their fast switching speeds but older mechanical types are way better for high power loads
 
The real trouble I have with electromechanical relays at the current levels we're talking about is the have input voltage and current requirements that most MCUs can't provide natively and nobody wants to build that kind of circuitry when you have an alternative.
 
bu_gee said:
The real trouble I have with electromechanical relays at the current levels we're talking about is the have input voltage and current requirements that most MCUs can't provide natively and nobody wants to build that kind of circuitry when you have an alternative.
Click to expand...

That's easy enough to fix.

Switch one of these relays with your PID.
http://www.digikey.com/product-search/en?KeyWords=PB1109-ND&WT.z_header=search_go

Then use the contacts in that relay to switch one of these.
http://www.digikey.com/product-search/en?KeyWords=PB1323-ND&WT.z_header=search_go
 
bu_gee said:
The real trouble I have with electromechanical relays at the current levels we're talking about is the have input voltage and current requirements that most MCUs can't provide natively and nobody wants to build that kind of circuitry when you have an alternative.
Click to expand...

I understand your concerns but it's no more circuitry than cascading a couple of relays. You can drive a small 5v relay with a FET and use the output of that relay to drive a high current relay with a 120V or 220V coil. Ya, It's more parts but its also more parts when you're replacing damaged ones.

Here's the large contactor for 13 bucks

http://www.ebrewsupply.com/40a-contactor.html

Here's the 5V relay for 2 dollars

https://www.sparkfun.com/products/100

Use a 2n7000 FET to drive the 5V relay from a PID or a microcontroller. About $1 in low quantity

That's probably the same price as a SSR but this system won't fail after an hour of use.
 
bu_gee said:
The real trouble I have with electromechanical relays at the current levels we're talking about is the have input voltage and current requirements that most MCUs can't provide natively and nobody wants to build that kind of circuitry when you have an alternative.
Click to expand...

pizza_man said:
That's easy enough to fix.

Switch one of these relays with your PID.
http://www.digikey.com/product-search/en?KeyWords=PB1109-ND&WT.z_header=search_go

Then use the contacts in that relay to switch one of these.
http://www.digikey.com/product-search/en?KeyWords=PB1323-ND&WT.z_header=search_go
Click to expand...

you beat me to it
 
Show me a 40A-240VAC relay that I can switch directly with 3.3V at 5mA and I'll use it. Hell, I'd settle for 15A-120VAC.

Plus, if you look at any of their datasheets they don't actually come close to a 5v solution, if that is what you're targeting (such as Arduino). Having a need for 4 different voltages in my system is simply unacceptable.

SSRs aren't about tossing the old because something newer has come along. They fit the needs of modern low voltage, low cost control systems that are no longer supporting power requirements of clunky electromechanical equipment.
 
Fotek equipment is reportedly a brand that is sometimes faked or sold as seconds in China. It is difficult to know if you have the real deal or a fake. I had one of the Fotek 40a SSRs in my system give up its magic smoke in the middle of a brew day and it was a scramble to finish the boil. I've since moved on to Opto22 SSRs which seem to be much more reliable and they are constructed in a manner that makes them undesirable to fake since they aren't a bit of metal plate with a cheap plastic cover. All cast metal and epoxy-potted.
 
Subdivisions said:
This SSR has a TRIAC output not a MOSFET. I looked up the datasheet. TRIACs are nice since they only turn off at the zero crossing of the sine wave. This prevents spikes or inductive kickback from damaging them. If you're having luck with the new relay then by all means keep with it. If it eventually fails then maybe think about an electro-mechanical relay. I think too many people get caught up in 'new' electronics and forget about the reliable past. Solid state relays are great for their fast switching speeds but older mechanical types are way better for high power loads
Click to expand...
I respectfully disagree with this argument since its not including the key point that the switching has to be done extremely fast and many times in one use.

My pids switch my ssrs multiple times a second to maintain consistent operation.... an old fashioned mechanical relay/ contractor would not work or last very long in this application... I have replaced many relays in equipment I service because the contacts burn up.... ssrs are superior for fast switching.

I am currently using one 20a "mypin" brand ssr and one 40a fotek ones and have had 0 issues with either driving two 4500 electric elements for 25 brew sessions or so now. I do believe the failure rate on these inexpensive ssrs is quite possibly higher than the expensive ones sold for 5 times more and thats why I bought an extra which I have never had to use.
 
I'm running some 50-amp dual channel Teledyne relays. They are pretty awesome. I was originally going to go with the cheap foteks like most people but I found these for $14 each with the fancy 4-pin connector for the 5v control voltage. They are potted and everything. The studs are for high voltage and the 4-pin is the control wiring. Each side is essentially its own relay. I use one of these for both of my pumps. Good deals can be found if you loom around. I think it is better to buy it once. This all assumes that your panel is wired correctly too.


 
augiedoggy said:
I respectfully disagree with this argument since its not including the key point that the switching has to be done extremely fast and many times in one use.

My pids switch my ssrs multiple times a second to maintain consistent operation.... an old fashioned mechanical relay/ contractor would not work or last very long in this application... I have replaced many relays in equipment I service because the contacts burn up.... ssrs are superior for fast switching.

I am currently using one 20a "mypin" brand ssr and one 40a fotek ones and have had 0 issues with either driving two 4500 electric elements for 25 brew sessions or so now. I do believe the failure rate on these inexpensive ssrs is quite possibly higher than the expensive ones sold for 5 times more and thats why I bought an extra which I have never had to use.
Click to expand...

Most PID controllers have an SSR "logic" output and a relay output. The SSR or "logic" output will do high speed switching, the relay output should be for more normal switch rates such as operating a compressor driven heating or cooling system. In brewing, there is absolutely no reason to use an output that switches hundreds of times a second. It offers no real world benefit.

H.W.
 
I dont think you can go wrong with Teledyne, Opto-22, or Crydom SSR's either and I've seen all of those in industrial applications. I've got a combination of Fotek and Aubers used in my brewery but used Crydom's in the past and have yet to have a melt down with either one of my 5500W elements at 240V.

A mechanical relay cannot withstand the cycling at load that an SSR does even only switching at once per second. The first RIMS system I built, I have an Omron PID with relay output only. Luckily it could be switched to thermostat mode instead of PID mode because the internal relay was constantly switching in PID mode.
 
mabrungard said:
Fotek equipment is reportedly a brand that is sometimes faked or sold as seconds in China. It is difficult to know if you have the real deal or a fake. I had one of the Fotek 40a SSRs in my system give up its magic smoke in the middle of a brew day and it was a scramble to finish the boil. I've since moved on to Opto22 SSRs which seem to be much more reliable and they are constructed in a manner that makes them undesirable to fake since they aren't a bit of metal plate with a cheap plastic cover. All cast metal and epoxy-potted.
Click to expand...


FYI:

http://www.prnewswire.com/news-rele...cognition-mark-release-13pn-52-242919311.html

You'll also find a thread on here that I started about reputable sources for SSRs; that thread includes a link to an eBay listing where a guy disassembled an eBay purchased Fotek that, in addition to being fake, was undersized.
 
Owly055 said:
Most PID controllers have an SSR "logic" output and a relay output. The SSR or "logic" output will do high speed switching, the relay output should be for more normal switch rates such as operating a compressor driven heating or cooling system. In brewing, there is absolutely no reason to use an output that switches hundreds of times a second. It offers no real world benefit.

H.W.
Click to expand...

Either I'm not understanding your explanation or you dont understand how the system actually works and maintains a consistent temp with the pid.

The pid controls when to actuate the relay by controlling the relay control voltage which either gives the ssr an on or off status by turning this voltage on or off.... Its how often that the ssr relay is turned on or off that determines the final power level and heating power of the element... the relay does not have or get any type of varied power from the pid.
therefore to maintain a specific temp the ssr relay is often turned on or off multiple times a in a very short time to precisely maintain that temp.... a mechanical relay is to slow to keep up and last without the contacts fusing or burning up from arching....
This is also why the pids with manual mode which allows one to lock in a set duty cycle which works better to keep a consistent temp without the constant fluctuations you would get with a slow switching mechanical relay. also this can keep the element from scortching the wort since the element never stays on long enough to reach its full temp and a much higher contact surface area temp once the liquid reaches the desired temp.
 
bu_gee said:
Show me a 40A-240VAC relay that I can switch directly with 3.3V at 5mA and I'll use it. Hell, I'd settle for 15A-120VAC.

Plus, if you look at any of their datasheets they don't actually come close to a 5v solution, if that is what you're targeting (such as Arduino). Having a need for 4 different voltages in my system is simply unacceptable.

SSRs aren't about tossing the old because something newer has come along. They fit the needs of modern low voltage, low cost control systems that are no longer supporting power requirements of clunky electromechanical equipment.
Click to expand...

For a 40 amp commercial / 50 amp residential relay look at one of these.
http://www.amazon.com/dp/B004Z0RLR6/?tag=skimlinks_replacement-20

To control the relay with 5 volts you will need another relay, something like this.
http://www.digikey.com/product-detail/en/C93401/PB1124-ND/1634010
 
Last edited by a moderator:
pizza_man said:
For a 40 amp commercial / 50 amp residential relay look at one of these.
http://www.amazon.com/dp/B004Z0RLR6/?tag=skimlinks_replacement-20

To control the relay with 5 volts you will need another relay, something like this.
http://www.digikey.com/product-detail/en/C93401/PB1124-ND/1634010
Click to expand...

4 voltages are still unaccepable when it can be done with two.

And if I even wanted to do it at 5V, which fewer and fewer people are, it still draws more current than most MCUs can provide on a single pin.
 
Last edited by a moderator:
mosstradamus said:
Before I built my 50 Amp e-HERMS panel, I spent a lot of time looking at designs that were posted on this sight, particularly PJs. I thought using circuit breakers within the panel, as well as contactors, was a little overkill....but based on what I was already spending, decided to keep them in the design.

I bought 40Amp FOTEK SSRs and didn't initially have a problem. After a couple of batches, I set my temp for the strike water at the beginning of my brew day, and then went about my normal preps. I returned to find that I had blown through the temperature and my strike water was 185 degrees. I used the contactor to kill power to the element, added some cold water to reach my strike temp and then re-energized the circuit. The BCS 462 maintained temperature for the rest of the day...without runaway temps.

On subsequent brew days, I continued to have the same problem. I verified that the 5V DC input from the BCS was appropriate, but the SSR was sticking open during the initial heating of strike water in my BK or getting my HLT to initial mash temp. If I killed the circuit with the contactor, the SSR would reset and didn't stick when energized for small temperature changes or maintaining HERMS temps.

I changed out the 40Amp FOTEK with another 40Amp FOTEK. I had good results for 3 brew days, and then started to experience the same symptoms. I hadn't gotten around to ordering new SSRs from Auber, and figured I could live with the sticky SSRs for a little while. With all the other projects I have going on...a little while turned into 6 months.

2 weeks ago, I was heating strike water in the BK and getting my HERMS water in the HLT up to temps at the same time. After 20 minutes of heating, the circuit breaker for the HLT popped. I looked inside, could smell something hot, but didn't see a problem. I continued the brew day, resetting both SSRs when the initial temperatures were reached and didn't have any further problems.

The next day, without the rush to get things done, I could see a little deformation of the HLT SSR. If I had seen it when I popped the CB, I would have called it a day.

My 40 Amp FOTEK running my fermentation chamber hasn't had any problems at all. I am making an assumption that the lower volts and amps aren't great enough to make the SSR stick....at least not yet.

3 out of 3 40Amp FOTEK SSRs installed on 25Amp circuits experienced sticking while bringing strike and heat exchange water up to initial temps.

A big fan of contactors and multiple circuit breakers in the panel....they have already paid for themselves.

Not a big fan of FOTEK.........I just switched to Auber.
Click to expand...

I would also redo the wire terminal connection. That is a classic sign of a poor termination building heat.

'da Kid
 
bu_gee said:
4 voltages are still unaccepable when it can be done with two.

And if I even wanted to do it at 5V, which fewer and fewer people are, it still draws more current than most MCUs can provide on a single pin.
Click to expand...

You might be correct, the relay coil draws 30 ma where a typical SSR would draw 20 ma. But 20 ma is also more current than most MCUs can provide on a single pin!!!! So, you would be setting up a transistor driver anyways and that driver can turn on a relay coil as easily as it can turn on a SSR.

And 4 voltages? Its still two voltages -5V on the first relay coil side and 240V everywhere else. The other relay I referenced has a 240V coil.
 
pizza_man said:
Interesting article that reads mixed results.
Click to expand...


Agreed. I'm sure the vast majority of people have had no issues but you should be aware that fakes exist (especially on eBay) and those fakes might not be built to the proper standards.

For something like a fermentation chamber that is running unattended, I wouldn't want a knockoff SSR to be a fire risk just because you were saving $15 in a hobby where most of us have thousands invested.
 
I've recently finished building an eBIAB setup. I bought a MyPin TD4 PID, which came with a 40A Fotek relay. I could get it to run and boil, but not actually control temps, or even limit the strength of the boil with identical behavior to what you describe. Researching the causes, and it seemed the thing everyone kept coming back to was a bad relay. I ordered a 50A, also Fotek. Same problem.

I tested the relay using a 9V battery, an extension cord, and a light bulb. Worked just fine. Hooked it up in my control panel, while still rigged with the extension cord and light bulb instead of the element. Again, all was perfect.

After some continued tinkering, I ran for a while with my control panel open, to watch for the light on the relay itself. I then realized that it was melting, in a very similar manner to your picture. The heat sink on it was clearly not cutting it.

I purchased a $5 PC water cooling block on ebay, a submersible statuary pump for $10 from a local place. Runs cool to the touch now, and everything is working as expected. It seems the relay was overheating, and would fail with the element circuit on.
 
I love these threads for the clash of opinion you get from everyone. Of course there is more than one way to skin a cat. Fortunately there are thousands of cats to keep trying. Poor analogy. I know.

From what I have seen in this thread it seems that the most likely culprit is simply heat derived from the SSR. That little thing should be able to run at 100% duty cycle for a good amount of time without overheating in the first place. This does not involve high speed switching or anything.

If you can't do that then you have a heat sink issue. Clean and clear. From the picture shown that is what it looks like. I hope you have good luck with your new SSR. A simple thermostat monitoring the SSR, placed in line with the power supply to the SSR to block current if it is going to overheat may be a good cheap investment for troubleshooting purposes.
 
Facinerous said:
I love these threads for the clash of opinion you get from everyone. Of course there is more than one way to skin a cat. Fortunately there are thousands of cats to keep trying. Poor analogy. I know.

From what I have seen in this thread it seems that the most likely culprit is simply heat derived from the SSR. That little thing should be able to run at 100% duty cycle for a good amount of time without overheating in the first place. This does not involve high speed switching or anything.

If you can't do that then you have a heat sink issue. Clean and clear. From the picture shown that is what it looks like. I hope you have good luck with your new SSR. A simple thermostat monitoring the SSR, placed in line with the power supply to the SSR to block current if it is going to overheat may be a good cheap investment for troubleshooting purposes.
Click to expand...
Except the OP stated he had the ssrs mounted to a heat sink with thermal grease... mine do not get that hot at all but I have a fan blowing through my heatsink.
So you dont believe in the existence of these inferior underrated knockoffs?
I have seen plenty of mofsets melt like that in audio amplifiers even when mounted to giant heat sinks... (I know that the ssr is not exactly a mofset)
 
It's also about the quality of the part, I have seen watlow din a mites work day in and out at 90% or more with only passive cooling and never miss a beat. That's what I use on my setup. Odd ball manufacturers out there may not produce the same quality product. Stick with trusted sources, a good maker of loose SCR's is Crydom.
 
atoughram said:
Some of the old CNC stuff that I used to service with DC servo motors used SCR's that switched dozens of times per second to feed a DC motor. A Triac is just two SCR's back to back so that it will work with AC, so I'd assume a Triac could switch pretty quick too.

DC Servo motors went by the way in the early 90's in favor of AC Servo's - which are glorified three phase stepper motors, an the SCR's were replaced by transistors I assume, although the early 90's were about the end of component troubleshooting.
Click to expand...

100% right. SCR/Triac switch in the Mhz. 60hz is nothing.
 
Hey. Not a brewer here, but I ran accross this thread while browsing and figured I'd chime in with my recent experience with fake FOTEK's.

For the curious, I threw together a bit of forensic analysis of the failure of my SSR-60DA here:
http://epicbeardquest.blogspot.com/2014/10/how-to-destroy-fake-fotek-ssr.html

While I'm here, and in reference to the "reputable sources" thread, this is the replacement SSR:
http://www.ebay.com/itm/381023889361
$31 for a Crydom 75A relay didn't seem like a bad deal, though I don't know how many of your setups need a 75A SSR.

Enjoy
 

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