Heating Circuit troubleshooting

AI Thread Summary
The discussion revolves around troubleshooting a heating circuit involving a microcontroller, SSR relay, and heaters. The main issue is that the heaters continue to operate even after reaching the temperature cutoff, indicating a potential problem with the relay or microcontroller output. The user has measured a low potential difference between the relay points and noted that the relay's LED does not illuminate, raising concerns about whether the relay is functioning correctly. Suggestions include reevaluating the wiring connections, particularly ensuring that the line is routed through the relay before the load, and confirming if the SSR is opto-isolated. The user seeks further guidance, possibly in the form of a schematic, to clarify the correct setup.
abhipatel
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Needed some guidance for my circuit:

Have a circuit consisting of a microcontroller + SSR relay + load (heaters)...issue is when the temperature reaches cutoff the heaters are not getting stopped and temp. keeps on increasing...

I have a connection of outputs from microcontroller into points 3 and 4 of the relay...all lives into point 1 and all neutrals into point 2.

Have tried to measure potential difference between points 3 and 4 and it shows in Millivolts? Another thing is the relay LED light does not come on...is it because the output is too low (relay is 0-5 V logic) or could it be that the relay is bad?

Am scratching my head as I do not want to order another relay if it is not the problem...is it my circuit or my relay or is my controller not giving enough o/p in DC to activate the relay?
 
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abhipatel said:
Needed some guidance for my circuit:

Have a circuit consisting of a microcontroller + SSR relay + load (heaters)...issue is when the temperature reaches cutoff the heaters are not getting stopped and temp. keeps on increasing...

I have a connection of outputs from microcontroller into points 3 and 4 of the relay...all lives into point 1 and all neutrals into point 2.

Have tried to measure potential difference between points 3 and 4 and it shows in Millivolts? Another thing is the relay LED light does not come on...is it because the output is too low (relay is 0-5 V logic) or could it be that the relay is bad?

Am scratching my head as I do not want to order another relay if it is not the problem...is it my circuit or my relay or is my controller not giving enough o/p in DC to activate the relay?

Would it be possible for you to post a schematic?
 
Am not much of an electrical guy but here it is in Word...see if it helps.
 

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abhipatel said:
Am not much of an electrical guy but here it is in Word...see if it helps.

I'm not understanding your connections. You would not put Line in one pin and Neutral in the other on the SSR. That would short Line to Neurtal when the SSR was turned on. You would run Line through the relay, then through the load to Neutral.

What SSR are you using? Is it opto-isolated?

http://en.wikipedia.org/wiki/Solid_state_relay

.
 
Could you please help me in figuring how to run Line through the relay, then through the load to Neutral in the form of a schematic or maybe just edit my diagram?...

I am still scratching my head and resorting to trial and errors...Thanks
 
This is a suggestion.
 

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