how to determine a shaft is running?

[osmanmom]

http://www.brantz.co.uk/PDFs/Manuals/BRH2_Manual.pdf

http://www.omega.com/pptst/DP2000-H.html

 

[JesperMP]

Not really clear is it. You have to sense "a shaft that runs on AC", I guess that it is an AC gearmotor to drive the belt or what ?

If it is really just a gearmotor that drives a belt conveyor, then this is a bog-standard application. We have exactly the same situation, also in a very dusty environment.
For the condition for the auger to start, use the motor starter contactor feedback PLUS a motion sensor on one of the belt idlers.

Do not use a motion sensor on the motor shaft, as it does not cover the situation that the belt is stuck. The motion sensor should also generate an alarm if the belt is stuck.
For the motion sensor, you can manufacture a plastic disk with metal pieces for a regular prox to sense on.
100 rpm is trivial, this can be reliably sensed with regular prox and PLC inputs.
If it was a really fast roller, then in stead of metal pieces in the plastic disk, you could make a half-moon, to get 50/50 pulse/pause periods.

Btw. in the olden days we also had special switches or relays that did the evaluation of the pulse timing internally. No need for that today, especially not at 100 rpm.

 

[osmanmom]

if the belt have ferrous jointed, install inductive sensor (stainless steel surface)

 

[Doug-P]

It could get a little pricey but,

a lot of uncertainty could be eliminated with a length sensor.

http://www.redlion.net/product/zfg-single-shaft-length-sensor-1-ppr

This way even if the belt breaks and the motor continues running you'll know about it and can take action. It'll even provide belt speed if that's needed.

 

[jdbrandt]

hi all
i am gathering some info for my little project and i am absolutely have no experience in electronics.

I would like to monitor a shaft(runs on AC) and if it is running then it triggers another motor(runs on AC). However I don't know what kind of sensor to use given that I cannot modify the exisiting system. All I have is a shaft.

I found I may possibly use a Hall effect sensor but I am not sure what type of Hall effect sensors is applicable as there are unipolar,bipolar,linear,latch and etc sensors.

I am thinking maybe any of them will do the job if the PLC(s7-1200) monitor the input values, say if the input changes from time to time in the last 5 seconds, then the shaft is running?

Any help is greatly appreciated.

Thanks

Back in the Old School, anti-plugging switches were used.

 

[osmanmom]

others option,

http://www.kiepe-elektrik.com/produ...ansducer-for-coupling/pulse-transducer-eog-dk

http://www.meyle-automacion.com.ar/pdf/conveyor-belt-monitor-6kb4111.pdf

http://www.lytteltonminingsupplies.co.za/Downloads/Voith/Catalogues/Conveyor-Motion-Monitor.pdf

http://w3.siemens.com/mcms/sensor-s...es/speed-sensor-milltronics-rbss.aspx#content

 

[kellian]

I would consider not monitoring the motor shaft , but monitor one of the non-driven belt rollers. As the shaft could be turning but the belt not moving due to a jam or ripped in half. This would then allow you to create a no motion alarm. ie motor contactor is closed but the belt hasn't moved.
You could check both driven and non driven pulley speeds, this would allow you to have a speed difference check (Belt slip) if the difference is too great then stop the process.

There is a Australian standard for conveyor systems which talks about what monitoring is required on conveyors.
AS1755