1794-OA16 off stage voltage question

angi

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Join Date
Jan 2010
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Hi Guys

I am using 1794-OA16 120VAC DO, when the output point is actived, I will get 120VAC, and I still got about 24V when the output was off, is this right? if not, what is the problem?

thanks
 
A solid-state AC output has 'leakage current'. For higher resistance loads you may see even higher voltage when 'off'. A very high resistance load may have so much voltage (that is they require so little current) that the 'leakage' is enough to keep the load turned on. You may see discussions of a 'load resistor' added in parallel to a load to lower its total resistance and prevent this lock up.

For solid-state AC outputs find the specifications concerning 'leakage' and possibly 'maximum load resistance'
 
The electronics of the output needs a minimum resistance to shut off, and if you're using a DMM for your reading it's resistance is too high.

In short, yes you will read some voltage leaking on an off output - if this is a problem in your situation spec relay outputs.
 
Thanks guys, I am using the output to trigger a relay, I can see the LED on the relay was on, but the dry contact of relay not been triggered even if there was no output, the contact will change status when output is on. from the application point of view, it is not a problem, but the LED will make electrician confused, any thought about this?
 
The specification for leakage

Off-state leakage current, max 2.25 mA

is enough to trigger an LED.

You will have to provide a parallel resistance to absorb part of that lowering the remaining voltage in the off state. This may prove to be cumbersome though. If the actuation rate of theese outputs is low then you could change to a relay output module.

Your reading of 24 volts implies a resistance of 10k ohms. Try paralleling the relay coil with a 10K ohm resistor (at least 1 watt rating). If that doesn't do it try a 5K ohm resistor.

Edit - Maybe a 2 watt resistor rating would be more appropriate.

 
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