# OPTO Boards



## Jlarson (Jun 28, 2009)

you mean a board like this 










?


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## Wireman191 (Aug 28, 2011)

Jlarson said:


> you mean a board like this
> 
> 
> 
> ...


 That is the one


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## Big John (May 23, 2010)

I've seen exactly what you're talking about because I got shocked the same way. _Larson_ might know better, but I think it's because those are high-impedance solid-state relays: They still pass current when off, just a very small amount.

-John


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## Wireman191 (Aug 28, 2011)

Big John said:


> I've seen exactly what you're talking about because I got shocked the same way. _Larson_ might know better, but I think it's because those are high-impedance solid-state relays: They still pass current when off, just a very small amount.
> 
> -John


 Ya wish i would have known before diving into them ya know, I hate screaming like a girl! I mean GRRRRRR!:laughing:


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## Jlarson (Jun 28, 2009)

Lot's of those solid state IO modules "leak by" because they is still some resistance across the output when they are off (if it has a snubber circuit that is usually the reason for most of the leakage though), but the leakage current is small like micoamps or maybe a few miliamps, can't say I've ever had it zap me. 

Lot's of times it's enough to slightly light an LED pilot light but put any real load on it like an incan pilot light, low impedance tester, motor, coil it kills it.


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## Wireman191 (Aug 28, 2011)

Jlarson said:


> Lot's of those solid state IO modules "leak by" because they is still some resistance across the output when they are off (if it has a snubber circuit that is usually the reason for most of the leakage though), but the leakage current is small like micoamps or maybe a few miliamps, can't say I've ever had it zap me.
> 
> Lot's of times it's enough to slightly light an LED pilot light but put any real load on it like an incan pilot light, low impedance tester, motor, coil it kills it.


 You have a site, or a key word I can use to look into them abit more? And thank you BTW!


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## Big John (May 23, 2010)

Jlarson said:


> ...(if it has a snubber circuit that is usually the reason for most of the leakage though)....


 What's the purpose of the snubber in those setups? Is there a kickback from the ballasts?

-John


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## Jlarson (Jun 28, 2009)

Crydom has some stuff on their site, plus you can look at some of the different SS relay options out there. 

Crydom, OPTO 22 and Grayhill are the common makers of those IO boards and modules if you want to look at them too.


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## Jlarson (Jun 28, 2009)

Big John said:


> What's the purpose of the snubber in those setups? Is there a kickback from the ballasts?
> 
> -John


Yeah to keep surges from inductive load switching from cooking the triacs. Some manufactures recommend you put a MOV on the output too.


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## LARMGUY (Aug 22, 2010)

Jlarson said:


> Yeah to keep surges from inductive load switching from cooking the triacs. Some manufactures recommend you put a MOV on the output too.


The MOV would also help to discharge any residual on onboard caps too correct?


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## Jlarson (Jun 28, 2009)

LARMGUY said:


> The MOV would also help to discharge any residual on onboard caps too correct?


 No, you need a bleed resistor on the caps if you have any in your circuit you want to discharge, unless they will discharge through the load.


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## don_resqcapt19 (Jul 18, 2010)

We hooked an alarm strobe to a solid state PLC output. The leakage current would charge the capacitor in the strobe and it would give a single flash about every 50 seconds or so. We add a standard pilot light in parallel with the strobe and the problem went away.


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## IBEW191 (Apr 4, 2011)

don_resqcapt19 said:


> We hooked an alarm strobe to a solid state PLC output. The leakage current would charge the capacitor in the strobe and it would give a single flash about every 50 seconds or so. We add a standard pilot light in parallel with the strobe and the problem went away.


 Thats wild! The thing the gets me is the power is there when not connected to a load, but when connected to the load the power goes away.


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## oliquir (Jan 13, 2011)

i like those solid states relay with their leakage it is good to identify bad fuses, i connect their output to input on plc and when fuse blow or load become open input is triggered.


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## Hamer (Oct 5, 2010)

We have an Opto22 board on one of our machines' setworks. I'm not sure who made it but it's in an Inovec (USNR) unit... yeah, hurts like hell.


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