How much heat sink?

[damfast]

i have a heat sink that came with the 40 amp ssr. Thanks for all your help ive been watching this site for a while now and it is a great help.

[BottleFed70]

Originally Posted by CarWiz

The rating doesn't mean a thing. It's the flashing power up cycle that will kill the power supply.

The rating means plenty, and don't forget that this is a constant duty rating. An AC adapter can and will provide higher pulsed currents. I really doubt that pulsing a 200mA fan is going to blow up my 1000mA adapter. Especially when the fan continues to spin between pulses (much less startup current).

Like I said, it's working fine and has for a while.

[CarWiz]

You don't understand the problem. The problem is NOT the load of the fan on the PS it's the constant jolting of the PS circuit itself. On start up, the filtering capacitor(s) look like dead shorts to the driver circuit. This is called inrush current. Constant switching reduces the PS lifespan--Like an incandescent lamp if switched on and off. Sure it works but for how long?

[BottleFed70]

Originally Posted by CarWiz

You don't understand the problem. The problem is NOT the load of the fan on the PS it's the constant jolting of the PS circuit itself. On start up, the filtering capacitor(s) look like dead shorts to the driver circuit. This is called inrush current. Constant switching reduces the PS lifespan--Like an incandescent lamp if switched on and off. Sure it works but for how long?

I understand the problem just fine. You'll notice in the post above that I even use the term "startup current". I think that the power supply is more than large enough to handle the demand.

[peter61]

I have a 3 2800 watt elements a 40amp breaker,10 gage wire,so far I've blown 2 40amp ssr's and 2 60amp ssr's,my wiring is the same as the wiring diagram posted on this forum,after using more heat sink on the 2nd 60amp ssr I set the oven for 150 degrees,it shut of then when the temp dropped below 150 it came back on but never shut off again,my ssr seems to shorted on the load side,although I can run my oven it won't shut off,HELP PLEASE!

[PhredAre]

Peter, If it were me, I would start from stratch and without attempting to energize any componets downstream of the PID, I would check voltage levels. First would be the AC to the PID, next would be the PID control to the SSR. This voltage should be DC and at a level compatible to the operating voltage of the SSR. If you find that this is AC then theres the problem. If this checks out OK, then, next you might take the TC and stick it in a cooking oven where it can be heated to a known temp and check out how the PID control voltage responds to the temp of the TC when you change the temperature set point on the PID. The next thing that you check would be the line voltage, both sides, to insure that they are at the normal operating level, I'm assuming that you are on a 240 volt system. Hope this gives you some ideas, each componet has operating parameters and all have to be compatible with one another. Fred

[ed_denu]

Peter,

First do as Fred suggests, then if you haven't found the problem and the PID checks out ok, look closer at your oven wiring. Since the ssr is repeated failing and you have an adequate heatsink, then the problem would appear to be in the input voltage to the ssr. Either the pid is bad, or perhaps you have inadvertently cross wired something allowing ac voltage to the ssr input terminals. If you could post a diagram of your wiring(do your own diagram, don't even look at the schematic you previously used) it would be helpful.

Also check to make sure the circuit supplying power to your oven is wired correctly. Is this a 3 or 4 wire setup and have you checked it throughly as Fred suggested?

Let us know what you find.

[PhredAre]

Peter, After pondering over night,and if every thing checked in the previous post, what is now needed is what size of panel and what size of feeder bkr is in the circuit that feeds the oven, how long is the feeder that supplies the oven( panel to Oven) and most important is the wire sized properly. If this checks out OK then we just about need a clamp on amp meter. I would be a little reluctant to just stick another SSR in and energize it. We need to know how the circuit performs under load and it would be nice to work up to the full load in steps. Like one element at a time. Its possible that there is low voltage on one legg of this circuit, hence the need to load in steps an monitor the voltage at the elements. the clamp on would also indicate this condition. If you were to find a low voltage on one legg it could be something as simple as a bad connection, a faulty feeder bkr, or maybe a fault in a feeder, under ground feeders are bad for this. You know that low voltage will cause a hi amprage condition and would cause heat buildup in the SSR. Fred PS, Good to hear from you Ed.

[ed_denu]

Good advice Fred. After going thru 4 ssr's I would test voltages every step of the way and not keep replacing parts and guessing on what the problem may be. If you are comfortable using a multi meter these tasks won't be that difficult. If not you need someone to assist you with this.

[CarWiz]

Can you post a picture of your control box? How is the heat sink mounted. Is the box closed or vented?