Shared transducer

ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I have several motors <=15HP that never run at the same time but I would like to get feedback when each does. The output goes to a plc. Not high accuracy requirement but it does initiate a shut down when parameters are exceeded. I would monitor one phase of each motor after its starter. Is there a reason I should not do this?
 
Why not monitor the auxiliary contact in the starter? Or if you need proof of motor operation, a CT switch in one of the t leads.
 
don_resqcapt19 said:
Why not monitor the auxiliary contact in the starter? Or if you need proof of motor operation, a CT switch in one of the t leads.
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I use the current to monitor a load(s) that can vary to the point of plugging an auger or conveyor. Plugging may result in burnt conveyor belts. I monitor RPM on some now, but not all. I’m no longer the EC. Just a programmer. More parts wait on the EC and he’s busier than I ever thought or wanted to be.

It’s a struggle to get an area millwright to put the weakest link at the start. Not midway or the end. This makes 5 years of equipment changes and may be the closest to fully automatic operation.

Eta. All motor starters are monitored via an aux contact.
 
Run one T lead from each motor through a single current transmitter, (or switch if you just need a digital, not analog signal) if all of the T leads are available at a common point.
 
herding_cats said:
Why would you only monitor one phase of each motor? Why nor all three?
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I don't need high accuracy. The motor starters all have properly set overloads for their protection. Under some conditions the belts or augers may plug and stall while the motors continue to run. Repair is a PIA. It's simple enough to monitor one leg and have feeds shut off if current is <or> than chosen set points.
 
ptonsparky said:
I'm not intentionally using it for single phasing although as quick as it can respond to 14.307 amps vs 14.3, there is no doubt it could serve as such. (Article you think I'm violating?)
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My doubt the sensed phase to motor there a break, other two phases to motor overloaded and not sense by plc.
The code demand protection for all three phases to motor, which article
 
Deltaforce said:
My doubt the sensed phase to motor there a break, other two phases to motor overloaded and not sense by plc.
The code demand protection for all three phases to motor, which article
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Deltaforce said:
430.37?
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I have the required protection for the motor via a standard across the line motor starter and overload.
I have one chance in three that I am monitoring a conductor that will suddenly carry no current.
Program logic can easily respond much quicker than the standard overload protection and I've used logic to detect no or low product flow to stop a process.
 
ptonsparky said:
I have the required protection for the motor via a standard across the line motor starter and overload.
I have one chance in three that I am monitoring a conductor that will suddenly carry no current.
Program logic can easily respond much quicker than the standard overload protection and I've used logic to detect no or low product flow to stop a process.
Click to expand...
Sorry, unnecessary setup , imho, plc by itself offer no motor overload protection, overload relay control by it do it
 
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