Motor Run Confirm
Motor Run Confirm
(OP)
We have a critical application with an Agitator that we are controlling through our DCS.
We recently lost the run confirm contact (only the contact....the starter was still closed) which shut down the agitator (due to the way we configured it in the DCS).
Is there any reason to have the Run Confirm used as a feedback to keep the agitator running, or just use the Run Confirm as indication only?
We recently lost the run confirm contact (only the contact....the starter was still closed) which shut down the agitator (due to the way we configured it in the DCS).
Is there any reason to have the Run Confirm used as a feedback to keep the agitator running, or just use the Run Confirm as indication only?
______________________________________________________________________________
This is normally the space where people post something insightful.





RE: Motor Run Confirm
I don't think that it is safe to answer that without knowing a lot more about your DCS scheme and the control philosophy behind the original design.
This may also be controversial. See thread830-151978
I have seen DCS schemes were a change such as you are contemplating would create safety issues. In other DCS systems it may not be a serious issue.
It depends.
yours
RE: Motor Run Confirm
The alternative is called "2-wire control" where there is some sort of maintained control device, such as a selector switch that stays in a "Run" position. If power fails and is restored, the motor will re-energize immediately, which may involve a serious safety risk.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Motor Run Confirm
Thanks for the refresher course!
Not only is a 2-wire control possibly a safety risk, but if there are multiple large motors (in our case), the electrical system may not be able to restart all of these at once after a power outage!
______________________________________________________________________________
This is normally the space where people post something insightful.
RE: Motor Run Confirm
http://www.veris.com/ Check out their Hawkeye series.
I have used them in aggitator applications. They can be set to operate at a current level greater than no load ( so you don't get a positive indication with a broken belt or drive shaft). I have had them installed in MCC buckets by the MCC vendor.
I am prettys sure any of the solid state motor starters can sense the same thing. If your running Device Net it should be a snap.
RE: Motor Run Confirm
They look interesting - I am always very wary of direct sensing relays, so a fully isolated type looks good. How do they compare cost-wise to a standard sensing relay with a cheap CT?
----------------------------------
I don't suffer from insanity. I enjoy it...
RE: Motor Run Confirm
Don