Here's an interesting failure mode for a temp controller

[Ravenshead]

I'm using a brand new Auber DSPR1 as a PWM for my brew pot with a 40 A SSR. It seems to work fine as long as I keep the duty cycle below about 60%. Above 60% the SSR appears to latch in the on position until I completely remove power from the system for a minute or two and then works normally for a while. I'm guessing my SSR is hanging in the on position due to thermal effects. Any EE's out there that can confirm that as a viable failure mode?

Here's the controller if you haven't seen one:
http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=444

 

[FuzzeWuzze]

As far as i know almost every SSR latches closed on failure.

That said its not desired obviously, it means something is wrong with your SSR. As you stated its likely not cooled enough, do you have a heatsink and or fan on it?

 

[ajdelange]

Does it feel hot or measure hot with a non contact thermometer?

 

[Ravenshead]

It has a heat sink that's external to the box. I've used it in a similar configuration with my PID for years.

One thing that may be a factor is that the backplane actually fell off while I was rewiring it. It was only held on by a tiny amount of an RTV-like glue, no thermal grease BTW. I re-glued with a little JB Weld. I'm wondering if a little JB Weld got between the baseplate and the circuitry and is interfering with proper cooling.

@FuzzieWuzie: I've had them fail hard closed but I've never seen them reset open upon cooling. Do you have any experience with that?

 

[spittybug]

Using a Fotek 40a SSR I had the same problem. The MyPin controller was showing that it was pulsing the element near the set point, and ultimately shut off once it shot past, but a quick eyeball of the element showed it chugging away! I had to manually switch off the box and then back on again.

The Fotek would get way too hot, even with a heat sink. Mine destroyed itself. It had the nasty effect too of ruining my GFCI breaker. It would lose the GFCI functionality! I ruined 2 of them before realizing it was related to the SSR. Must have somehow fried the GFCI circuitry. Luckily they have 10 yr. warranties and HD took them back.

I'm now re-doing my control box with the Teledyne SSRs mentioned on other threads. These are much better potted, heavier and all around seem better. I'm also going to go with a contactor to use as the main switch as I've learned that a simple go-to-ground emergency stop button only works if your GFCI works! Since the Teledynes are so affordable, I'm also considering splitting load just to keep them as cool as possible.

 

[Ravenshead]

Yeah, the Fotek brand has a problem with counterfeit parts but I've been able to get them to work pretty well. This one was a name brand SSR from Auber though. Where are you finding affordable Teledynes? They seem to run $60 a piece from what I can find.

 

[spittybug]

http://www.ebay.com/itm/TELEDYNE-SD24R50-280VAC-50A-SOLID-STATE-RELAY-NEW-/321711347394?pt=LH_DefaultDomain_0&hash=item4ae77d96c2

Haven't used it yet since I'm still re-building the control box, but seems really beefy and well potted. Each SSR can handle two legs. I ordered 2 units and 4 arrived........... 8 legs switchable!

I electrically tested them and believe them good. There is a slight concaveness to the bottoms that can probably be sanded flat. Maybe they are factory rejects because of that?

 

[Ravenshead]

Nice, I just bought two.

 

[BetterSense]

I had the same thing happen with a generic SSR. I ended up installing input and output indicator lamps side by side so I would be able to see failures like that easily.

 

[acidrain]

Wow, great price on the Teledyne... I just bought 2.

 

[BlkWater_brewer]

Yeah, the Fotek brand has a problem with counterfeit parts but I've been able to get them to work pretty well. This one was a name brand SSR from Auber though. Where are you finding affordable Teledynes? They seem to run $60 a piece from what I can find.

$60 may seem expensive, but I had a generic SSR fail in the latched state in my RIMS circuit. The first 3 steps went fine, the final step at 164 didn't. Before I stopped it the temp had shot up to 180. With 40lbs of grain, that $60 looks dam cheap.

BTW, I have a temp monitor mounted next to the SSR's and the temp never made it past 138 degrees in the controller.

Will be brewing an additional batch tonight to blend in the fermentor. The Brett should take care of un-fermentables but lesson is no more discount knock-off parts, including re-branded Chinese parts.

 

[Ravenshead]

I buy most of my grain in bulk buys by the pallet so 40 lbs. of grain only costs me about $12. The time wasted is a problem though.

That said, I just bought two of the open box Teledynes for $15 each. Win-win, as far as I'm concerned.

 

[BlkWater_brewer]

I buy most of my grain in bulk buys by the pallet so 40 lbs. of grain only costs me about $12. The time wasted is a problem though.

That said, I just bought two of the open box Teledynes for $15 each. Win-win, as far as I'm concerned.

40lbs for 12.00, Yea if I was using the cheapest 2 row around. I should look into a group buy sometime. Picking it up at cost from my local brewery doesn't come close to that price - even at the 32K pricing.

But eBay did have a good deal on Teledyne SSR's for sure.

 

[Ravenshead]

Well, I took apart my controller and my suspicions were correct. A little bit of the JB Weld that I had used to repair the SSR in question had indeed oozed between the circuitry and the base-plate. There was even evidence of a little charring where the JB weld was present. So much for that unit.

 

[spittybug]

Should one of the Teledynes, mounted with thermal paste onto a good sized heat sink still require a fan on it? Only running one 5500W element at a time and the Teledyne is rated for 50 amps. The enclosure isn't very big (10x8*3 or so). Maybe just knock out a couple more of the pre-punch holes to let heat out?

 

[Ravenshead]

I've run them for years with the standard heat sink mounted outside the box without a fan without issue. That's in Houston summer weather BTW. This thread dealt with a special case.

 

[RichBenn]

Nothing wrong with the fotek; BIG problem with the Fotek counterfeits. There are pics on how to tell if you have one.

 

[Ravenshead]

The Teledynes came in and I'm impressed. First off, I ordered two and they sent me four. Then I noticed that each unit is actually the equivalent of two of the normal ones. So now I have the ability to control up to eight channels. I won't need to buy an SSR ever again.

 

[-CHRIS-]

Nothing wrong with the fotek; BIG problem with the Fotek counterfeits. There are pics on how to tell if you have one.

How about a link on how to identify the counterfeits?

Chris

 

[Ravenshead]

There are lots of them. Just Google counterfeit FOTEK SSRs.

 

[spittybug]

After trying my luck with Ebay parts, I bit the bullet and now have an Auber PID controller and a Teledyne SSR running the system. I sanded the base of the SSR flat (a little convex) and made sure to have sufficient heat paste between it and the large heatsink. I also added a computer fan on the control panel to keep things cooler. It's 85+ here in Houston right now and my control box is sitting at 92 while I'm calibrating/setting up the new controller. I also didn't like putting the wire ends into the switch connectors so I put small gauge "forks" on each one and they stay connected nicely. $4 well spent, but time consuming. Each is soldered and has heat shrinking over the joint. No chance of anything shorting when the door is closed.

First thing I notice is that it cycles far less frequently than the Fotek/MyPin combination did and after autotuning it, it barely overshoots (~1* max). I can live with that!

I found that not only was the old Fotek fried but the MyPin was flashing his output lamp but the output voltage was continuous!! No wonder the thing ran away and self destructed. On a positive note, the 2 beers I made (at least mashed) on electric (had to finish with propane) and using the new fermenting chamber came out great! A nice Irish red and a Bombshell Blonde knockoff. I'm very pleased. The mashing temps went too high too quick and I ended up getting a higher FG than targeted, but I like them malty and it was a lucky mistake. Next up, a big Belgian. Maybe I'll name it "Third time's the charm".