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Thread: Current switch confusion

  1. #1
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    Current switch confusion

    I have a motor's status showing as being "on" when there's no command for it on the BAS. The motor is stationary and is not spinning. I swapped the current switch with a spare on site since it was easy enough to do and the status comes back to being "on". I'm a little confused as to the NO terminals on the switch (hawkeye 934). It has the 24v coil terminal, a N.O 'status' terminal that's wired to the binary input on the controller (Metasys), and another N.O terminal that's wired into a terminal block within the VFD (didn't trace out the wires). When I unplug one of the status wires, it shows as being off. When I send a command for it to run, the LED blinks normally. I tried checking voltages between that switch and a switch in another VFD with the same set up and I can't seem to find any difference. Anyone have any ideas as to what could be causing that status switch to close?

    Per the specs:

    (On/off, Status only) .................................................. 5-34 Hz................................................ ..................................... 3 to 135A

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  3. #3
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    Thread Starter
    Thats the one. It has two N.O contacts, one for .1A and one for 3A. Even when I remove the load wire from the sensors core, the status is still on. When I remove the 24v for the coil, I check continuity on both of the outputs and get nothing

  4. #4
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    Looks like it's a "smart" sensor....did you put it in learn mode with the motor running? It has to self calibrate.

    also, there's a short note on that sheet that says it doesn't ohm out like a standard relay, so it's likely a triac output.

  5. #5
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    I would suggest requesting this post be moved over to the controls forum. Most of us are fairly familiar with many types of CT's for proving motors, electric heater, compressors, etc. but this particular one with internal learning and utilizing what appears digital triggering of the status through maybe a triac, is beyond me a bit. Could be that a resistor needs to be installed or something simple that a control guru, who sees this stuff day in and day out would know?

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    Chops, you beat me to it

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    I returned back to the site and went through the calibration part. It still had the same issue. I was close to telling them they need to replace the motor, VFD and BAS, but decided to try another spare they had on site and it appears to be working as intended. I’d like to think that I replaced it the first time but part of me feels like I took the old one out and put it back in. Thanks for chiming in guys

  8. #8
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    Quote Originally Posted by JTLB View Post
    I returned back to the site and went through the calibration part. It still had the same issue. I was close to telling them they need to replace the motor, VFD and BAS, but decided to try another spare they had on site and it appears to be working as intended. I’d like to think that I replaced it the first time but part of me feels like I took the old one out and put it back in. Thanks for chiming in guys
    I must have missed something, I thought your dealing with a flaky hawkeye current sensor, why if the sensor is in question, as outlined in your post, would you go to the extent of replacing the freak drive, motor, and possibly the Building Automation System?

  9. #9
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    Quote Originally Posted by slctech View Post
    I must have missed something, I thought your dealing with a flaky hawkeye current sensor, why if the sensor is in question, as outlined in your post, would you go to the extent of replacing the freak drive, motor, and possibly the Building Automation System?
    The new techs.........
    Change enough and it will work!

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    Quote Originally Posted by JTLB View Post
    I returned back to the site and went through the calibration part. It still had the same issue. I was close to telling them they need to replace the motor, VFD and BAS, but decided to try another spare they had on site and it appears to be working as intended. Id like to think that I replaced it the first time but part of me feels like I took the old one out and put it back in. Thanks for chiming in guys
    Its just a set of dry contacts, should be easy to confirm its operation before condemning other components.

    Use caution sufficient to protect you from whatever voltage is being switched by this relay...

    Confirm the problem by disconnecting the wires and checking for the correct corresponding feedback for what an open contact would look like. Close the wires together and confirm the proper input is again received.

    If the BAS is sensing your simulated triggers then its not a motor or VFD issue, its a relay issue and you need to replace your current relay.

    This above method will only work if this relay is wired in series with everything else on its circuit. If there is a switch wires in parallel then you should also be looking at that switch too.


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    Quote Originally Posted by pecmsg View Post
    The new techs.........
    Change enough and it will work!
    I refer to them as "Replaceman" (aka parts changers) rather than Repairmen.

    I much prefer to program/use the On-Board Relay Output that indicates "Drive Running". Most drives have one, some can be setup to indicate actual Torque.
    If sense were so common everyone would have it !
    Never underestimate the power of human Stupidity !
    If folks took care of their cars like they do their HVAC Systems you'd see a lot more people walking !

  12. #12
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    Quote Originally Posted by pecmsg View Post
    The new techs.........
    Change enough and it will work!
    Everybody starts somewhere........

    and I'd be lying if I said, I've never taken that approach on a piece of equipment! LOL!!

  13. #13
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    Quote Originally Posted by JTLB View Post
    I returned back to the site and went through the calibration part. It still had the same issue. I was close to telling them they need to replace the motor, VFD and BAS, but decided to try another spare they had on site and it appears to be working as intended. I’d like to think that I replaced it the first time but part of me feels like I took the old one out and put it back in. Thanks for chiming in guys

    You've got to stop and break things down into basic components. Nothing in a control system happens without something giving it information......you just have to break each part down and figure out where the information comes from and what its' causing to happen.

    everything was working except the motor status. so, go through the process......is the control system telling the motor to start? (yes), is it starting? (yes)......is the control system being told the motor is running (NO!).......by that process, the control system, motor and drive MUST be good. the drop in the chain is the CT, so regardless of all else, it MUST be bad.

    I've also had new parts be bad out of the box, so never assume anything.

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