1769 OA16 Changeout questions

Hello every one. An output on the 1769 OA16 card on our sootblower micrologix PLC has failed in an always on state. There was believed to be some grounding issues in the field which I think led to this happening. I'm positive its not being activated via the program and the LED indicating light on the front of the card isn't lit, even though 120v is constantly coming out of the output. Unfortunately all outputs are being used and there are no spares. The only option at this point is to change out the card. I don't do a hell of a lot of work with Micrologix PLC's, to change out this card I know I have to shut down the PLC and its the 5th card in from the right so I have to unlatch all cards prior to this one to remove and replace it. My question is; Is this card just plug and play, I don't need to configure anything in the PLC? I'm replacing it with the a new card which is the same 1769 OA16 output card. Reason I'm asking is we have to take the PLC down and by doing that our operators will not have automatic control over the Boilers soot blowers so down time needs to be kept to a minimum. Thanks, TEX

There is nothing to configure.

You are aware that this card is a solid state output so there will be voltage ( do to leakage) even though the output is not turned on. Does the load energize also with the output off? What is the load?

Mickey said:

There is nothing to configure.

You are aware that this card is a solid state output so there will be voltage ( do to leakage) even though the output is not turned on. Does the load energize also with the output off? What is the load?

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I'm aware of leakage, but not 120v's. There's steady 120v's coming off the output at all times, the other outputs have relatively nothing in their off state. The load is a contactor coil. But I had just taken the wire off the load and still there's 120v's from the card.

If the part number is an exact match, and you're installing it in the same position on the Micrologix you should be in good shape. I don't have one of those on hand right now, but I know that some of the older AB I/O cards have removable terminations, so if the terminations are still good you could avoid rewiring by taking it off as a block. Again, I can't remember if the Micrologix I/O works this way but I think I remember that SLC I/O did.

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sparkytex said:

I'm aware of leakage, but not 120v's. There's steady 120v's coming off the output at all times, the other outputs have relatively nothing in their off state. The load is a contactor coil. But I had just taken the wire off the load and still there's 120v's from the card.

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An inductive load like a contactor's coil should be enough to pull the leakage down when the output is off.
You will see full voltage with no load connected.

Does the contactor stay on when the output is off?

I'll go over and run a test. I cannot just just energize the contactor, because the soot blowers need to follow a certain sequence. I know I can remove the motor leads but if I get caught doing that i'll be in trouble. (even though I am an electrician, I am no longer in the union as one, so it would be considered crossing trades). However I can bring over a 120v contacter and hook up a neutral to one side of the coil and run a jumper from the PLC's "failed" output to the other coil contact and if the coil energizes i'd say for certain that the output has failed.

upon further investing the suspect output, I remembered the shift electrician that was on today has a wiggy. We used that on the output and realized that it was indeed leakage. Your a smart man Mickey, may have saved some down time!! Thank you for taking the time to help mickey and Ben

sparkytex said:

upon further investing the suspect output, I remembered the shift electrician that was on today has a wiggy. We used that on the output and realized that it was indeed leakage. Your a smart man Mickey, may have saved some down time!! Thank you for taking the time to help mickey and Ben

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You're welcome.