Ssr temp

[Kwitty]

New to electric brewing. First time set up on my new home built set up. I'm 120v, 2200w element, Inkbird ITC-106vh with Inkbird 40a relay and heat sink.
Heat sink is getting hotter than I expected while rising to set temp. Heat sink Temps are around 150/160F or 60/65c. I'm not sure what normal is supposed to be? I hear lower temps normally but they are mostly running 220v and I'm sure there's a difference. I just don't want to set stuff on fire!

 

[doug293cz]

Your SSR shouldn't be getting that hot. Could be poor thermal interface between SSR and heatsink, or inadequate air flow across the heatsink. Can you post some pics from different angles of your SSR & heatsink?

Brew on

 

[Kwitty]

Sorry doug293cz. Might be a day or two for pictures. However those temps were taken at the base of the heat sink sticking out of the control panel. Wondering if I have a bad ssr? I'll double check everything but I don't know what else it could be? If it were hooked up wrong I would think it just wouldn't work?

 

[Genuine]

I'll have to measure mine and see what temp it gets to on my 240v System. I can usually keep my hand on mine but there are points where it gets a bit too hot to touch.

 

[augiedoggy]

Theres the unproven commonly spread suggestion here that along with being easier on the ssr (which is true) a higher amp rated ssr somehow generates less heat than the one that would normally be the closes match to the load, if that were not true then It really wouldnt matter what the load is on the ssr so much and if your just using one of the $2 din rail type ssr heatsink (same heatsink whether you pay $2 on ebay or $11 from the popular reseller many buy from here) it will get very hot without a fan to cool it.

Also, all bets are off if your using one of the knock off fotek clones which often have components only rated for 10amps inside of them.. its a total crap shoot with them whether they will hold up and for how long. and since they would be overloaded even with a 2200w 120v element they would get hot.
I'm going to go out on a limb here and assume your using the inkbird branded ssr which is made by one of the same manufacturers that make some of the fotek clones so...

I have those foteks as well as a mypin branded ssr in the first panel I built. They still work. also the mypin and fotek ssrs had the same manufacturing markings and were identical other than the sticker. some of the clones are made better than others and its hard to know what is what.

 

[dmwahl]

Theres the unproven commonly spread suggestion here that along with being easier on the ssr (which is true) a higher amp rated ssr somehow generates less heat than the one that would normally be the closes match to the load

It's true, the reason being that while a 20A SSR and a 50A SSR may have the same theoretical voltage drop, there are many factors that affect temperature. Two big ones are below...

1) Ohm's law. The SSR will not just be the switching component, the connections between the switch (usually triac based) will also have resistance and the conductivity of those connections will be greater for a higher rating SSR. Not only that, but the switch itself will have some ohmic losses that lead to heating and will be lesser for higher ratings.
2) Heat transfer out of the SSR will be better for higher rated parts. Lower thermal resistance will lead to lower temperature.

Personally I suggest the following when selecting an SSR:
1) Use a name brand SSR (Crydom, Panasonic, Omron are all respected brands) from a reputable electronics distributor (Digikey, Mouser, Newark, etc).
2) Get one rated for double your intended current. SSRs can get stuck on at too high of a temperature and the ratings are based on optimal cooling, not a passively cooled heatsink like the ones often packaged with cheap SSRs.

A good SSR will cost you $50 or so, but it will last forever if treated well. Given the other costs with an electric brewing system I don't see much reason to skimp on such a critical item.

Back to the OP's question, heat generated by the SSR is due to current, not voltage. The reason 220/240V systems tend to be cooler running is that for the same amount of power output the current is half what it would be for a 110/120V system. While admittedly a rule of thumb, you should be able to comfortably touch the heatsink.

 

[augiedoggy]

I just bought a lot of 25 used 25a crydoms for $27 on ebay so there are good deals out there...

as for the mix of 40 and 25a ssrs I have in my panels now, I notice no difference in temp at the heatsink between the two.. but I have a fan.

in all my years here the only ssrs I can ever remember reading about failure here are the white fake fotek and rebranded variants.
I have never seen reports of one of the cheaper mgr variants like ebrew aubrins or ebay sell fail from memory but thats just my observation.

 

[Sparkncode]

If you use a good brand name SCR they is really no need to buy a device with a current rating way over your intended load. A bit of margin is good but no need to go overboard as it adds unnecessary cost.
I run 25A SSRs on a 20A load passively cooled setup and have no heat issues.
A good heatsink helps with this.

If I was trying to use suspect SSRs then twice the rating is sensible.

 

[augiedoggy]

For what its worth..
I have a 120a 3bbl panel which I had installed 40a MGR mde (berme brand) ssrs in there are 5 on the left and 4 on the right connected to the exact same size heat sink mounted on each side of the panel. only 4 come on at a time to heat either the HLT or BK and the fifth is the rims.

Anyway, I bought the lot of 25 crydom 25a ssrs because I want all the ac components to be UL listed for the inspector and the mgr made ssrs like auberins and ebrew sell are not apparently (CE only )... so I swapped out the right side ssrs and ran the HLT up to 150 degrees with the crydom 25a ssrs... Then I heated up the BK to 150 using the 40a ssrs on the left.... The heat coming off either heatsink felt identical to me.. it was hot enough where if it was a few more degrees it would be too hot to keep my hands on for a long period of time. This is with a 23 amp load on each ssr.

 

[tellyho]

I am on my third ssr in a simple pwm controller. Heat has always been an issue, and I've redesigned my box twice now. Heatsinks and thermal paste alone did not solve the problem, nor did a bigger box. Finally settled on wiring in a bigass computer fan - no heat issues.

 

[augiedoggy]

I am on my third ssr in a simple pwm controller. Heat has always been an issue, and I've redesigned my box twice now. Heatsinks and thermal paste alone did not solve the problem, nor did a bigger box. Finally settled on wiring in a bigass computer fan - no heat issues.

what ssr?

 

[doug293cz]

I am on my third ssr in a simple pwm controller. Heat has always been an issue, and I've redesigned my box twice now. Heatsinks and thermal paste alone did not solve the problem, nor did a bigger box. Finally settled on wiring in a bigass computer fan - no heat issues.

Have you posted pics of you previous builds? Might be useful to others as examples of designs that don't work well. Maybe you can help some others avoid having to go thru the iterative process you went thru.

Brew on

 

[Brewbuzzard]

I built a 60 A 240V panel employing 4 40A SSRs and a large passive heat sink. I only allow two 5500 watt elements to run at one time. Each element draws about 22A at 100% output. I have no heat problem. I assume you used the transfer grease between the SSR and heatsink...
I was very lucky and found the heatsink at Tanner's Electronics collecting dust for $15 buck!

 

[tellyho]

Have you posted pics of you previous builds? Might be useful to others as examples of designs that don't work well. Maybe you can help some others avoid having to go thru the iterative process you went thru.

Brew on

One is scrap - too many hot things in too small an enclosure. I'm on my second iteration of the larger version. Key has been computer fan run by 9v converter, pulling through punchouts across the heatsink for my ssr. 240V PWM circuit.

 

[augiedoggy]

One is scrap - too many hot things in too small an enclosure. I'm on my second iteration of the larger version. Key has been computer fan run by 9v converter, pulling through punchouts across the heatsink for my ssr. 240V PWM circuit.View attachment 605157View attachment 605158

You never told us what brand of ssr your using here? it does matter if your attempting to use the white generic ones, branded as foteks which often contain components that are only rated to 10a regardless of the sticker they put on them. lots of failures here with those. other brands not so much.

From these pic it appears your are not using an SSR but rather an SSVR with a potentiometer? or are you trying to use a regular ssr here? I was under the impression they wont work with this kind of variable resistance control?

 

[augiedoggy]

I built a 60 A 240V panel employing 4 40A SSRs and a large passive heat sink. I only allow two 5500 watt elements to run at one time. Each element draws about 22A at 100% output. I have no heat problem. I assume you used the transfer grease between the SSR and heatsink...
I was very lucky and found the heatsink at Tanner's Electronics collecting dust for $15 buck!

I do the same on my 3bbl panel only with 4ssrs running at once on a single heat sink.. no issues.

 

[day_trippr]

It's all about RDS(on), and SSRs are definitely not created equal...

Cheers!

 

[tellyho]

You never told us what brand of ssr your using here? it does matter if your attempting to use the white generic ones, branded as foteks which often contain components that are only rated to 10a regardless of the sticker they put on them. lots of failures here with those. other brands not so much.

From these pic it appears your are not using an SSR but rather an SSVR with a potentiometer? or are you trying to use a regular ssr here? I was under the impression they wont work with this kind of variable resistance control?

I believe I tried a cheapish SSR in one iteration. Current one is not a cheapy. Controller is a simple PWM circuit, designed and built by my electrical engineer father. Basically the electric version of stove top - turn it up or turn it down.