detecting rotation of motor

Google "zero speed switch" or sensor.

Yes---A zero speed switch?

Do you have PLC control or a hard wired motor starter with aux. contacts?

Is the motor coupled to something else.

There are a lot of options.

K T

Zero-speed sensors present an interesting challenge: From a ZS sensor's point of view, what actually constitutes zero speed? That is to say, is there a shaft RPM greater than zero but below which a ZS-sensor (however implemented) would indicate that the shaft is not rotating when, in fact, it is rotating, albeit slowly? In some applications this could have disastrous consequences, as you can imagine.

We use an ordinary proximity sensor in some of our motors. A timer receives the pulses and is continually reset each time it receives a pulse. If the pulses stop, the timer runs through and triggers an alarm.

For most of our motors, we have current sensors. We sense over-current as well as under-current. Whichever alarm is triggered, we investigate.

regards,

Vulcan

zero speed may be a catch phrase of sorts.

We use every kind of imaginable means to interlock equipment using motion sensors, physical limit switches, inductive prox switches, photo eyes, opitcal roto pulsers and even some analog positioning with encoders, servo, serco control inputs to PLCs---you name it.

I wasn't comfortable with "zero speed switch", the first time I heard it--But I knew what it was and just adapted to the term.

Here's a possibility:

http://www.ab.com/safety/prod_directory/interlock_switches/guard_locking_switches/cu2_stop_motion_det/

The time for determining that rotation has stopped can be extended to up to 40 minutes - trouble is, if it was keeping a guard locked, you'd have to wait for the preset discrimination time (up to 40 minutes) before you could open the guard!

Which is this application, where supply is ON, but motor is not running?

Which is this application, where supply is ON, but motor is not running?

In fact I want to switch off the supply of motor if it stops running (due to any fault condition).

Reasons for a non rotating electric motor:

• No terminals voltage at all → No problem, no need to switch off
• Locked rotor condition → Motor current must be much more higher than normal running. The current value can be used to trip the motor
• In a three phase motor, one of them is out → Motor in two phases cannot run and current is higher as in the previous case. Similar solution

Kind regards

We use current sensing switches made by Hawkeye. They can be purchased though Kele Controls.