PLC wizards -- help identifying sensor?

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drcampbell

drcampbell

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Location
The Motor City, Michigan USA
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Registered Professional Engineer
I'd like some help identifying this sensor.

It's mounted behind a big pulley that will turn about 600 revs/minute, that has one big iron slug that passes close by the sensor with each revolution. The label is either missing or completely unreadable.

It's called a "revolution guard" in the (somewhat sparse) documentation. I suspect its purpose in life is to turn off the drive motor in case the machine stops turning because something jammed or broke. It's a 90 kW motor, which could wreak considerable havoc.

It was originally configured for 220 volts, 50 Hz. (Denmark) I hooked it up to 120 volts, 60 Hz and a small linear load. (a 7-watt Xmas-tree bulb)
It turned on the lamp for about 20 seconds, then turned it off. The red LED on the back of the sensor lit up at the same time.
Turning the pulley by hand (~1-2 revs/minute) and passing the iron slug slowly past the sensor did not elicit any response. Both lights remained off.
The same thing happened when hooked up to 220 volts, 60 Hz and two Xmas-tree bulbs in series.

I have the book for the controller, but not the controller. I'm in the process of building a new controller.

rg-sensor-side.jpg
rg-sensor-front.jpg
rg-sensor-back.jpg
revolution-guard-wiring-diagram-highlighted.jpg
revolution-guard-wiring-diagram-highlighted.jpg


https://i.postimg.cc/TpZJRLWh/rg-sensor-side.jpg
https://i.postimg.cc/LhQVb09t/rg-sensor-front.jpg
https://i.postimg.cc/hfJ0WbvH/rg-sensor-back.jpg
https://i.postimg.cc/D40Pz1g4/revolution-guard-wiring-diagram-highlighted.jpg
https://i.postimg.cc/D40Pz1g4/revolution-guard-wiring-diagram-highlighted.jpg
 
Um, right.

I need to know more than just its name.
Is this normal behavior, or is my sensor broken?
Does it require a sneak ground, like some older lamp dimmers? (the mounting nuts are plastic and the mounting bracket is painted and corroded)
Does it require the iron slug to pass by the sensor much faster than I can turn it by hand in order for it to respond? (I can't run the machine yet)
Can somebody point me to a spec sheet that spells out details for this or a very-similar sensor?
 
Make sure you are using the correct voltage, AC or DC. We can't tell from here. It looks like a 2 wire. Connect a small interposing relay of the proper voltage. Pass a screw driver directly in front of the sensor. They have a sensing distance. Does the relay pull in? It works. The ones I use are normally open. It could be reverse operation, meaning relay will pull in with no target and drop out when target is sensed.

You could have damaged it already but you would be the first one of us to have done that.
 
181108-1440 EDT

drcampbell:

Does it have an internal magnet? Looks like 3 wires to it. If so how were these connected? And what probable voltages? What do the wires interface to?

Since no output on slow motion it implies a magnetic sensor where there is a magnet somewhere and a pickup coil, and possibly nothing else. This would be velocity sensitive. Also might include some electronics.

I used a sensor once with a magnet, coil, transistor, and three wires. Below a certain velocity and distance coupling no change of output state. Above this threshold velocity condition fairly sharp change of state. Duty cycle would change with velocity.

A plain coil and magnet sensor has two wires, and has an output voltage that is proportional to velocity, e = k*N*dv/dt.

In automotive ABS systems both velocity sensitive (coil and magnet), and Hall or magnetoresistive sensors have been used. Early Ford units with the tone ring inside the differential used a magnet and coil. Thus, velocity sensitive. About 3 MPH was the cutoff point.

Most sites I looked at on the internet gave a very poor discussions on theory.

You need to tell us exactly how your device was used in the circuit.

There used to be a company with a name like Electro-something that made a velocity sensitive unit with a transistor output. I can't find it.

The following does not seem to be the company.
https://www.electro-sensors.com/products/shaft-speed-sensors/600-series-proximity
No good discussion on basic theory of operation. Typical dumbing down of connection to a thinking customer.

There are many different solutions to your problem. Many sensors will do what you probably need.

.

.
 
You may also look at zero speed switches if you need to replace it. I have seen those used on screw conveyors to detect a broken shear pin in the motor coupling... If the pin breaks the motor still runs, screw conveyor stops, and interlocks then go on to stop all upstream equipment.
 
181108-1612 EST

drcampbell:

Your circuit diagram does not help much. It may imply the sensor is a two wire device controlling a relay.

Is the relay really an electromagnetic relay coil? What is the voltage? What is the coil resistance? What is inrush current?

What is the air gap between the sensor and the slug of metal on the flywheel?

If you move a piece of iron/steel (not stainless) rapidly by your sensor does it change the relay state?

When the sensor is not activated what is the current magnitude thru the sensor and/or relay coil?

If you monitor the relay coil voltage with a scope what happens when a piece of steel is rapidly moved by the sensor?

.
 
The part number is right there, XSAV-16111, it’s a proxy sensor from Schneider. It is obsolete but Schneider’s website identifies the replacement as XSAV11801. That Accepts any input voltage from 24 to 250V so it should be fine. It is adjustable from 6 to 1000 CPS so if it doesn’t see its trigger at the set rate, it will not change state. But it takes approx 9 seconds from power up to start detecting, do that’s likely what you saw.
https://www.schneider-electric.com/en/product/download-pdf/XSAV11801


The part number for that relay is an old obsolete electromechanical relay from Siemens with a 220V coil. That would need changing.
 
181108-2133 EDT

This device is not a prox switch, but it might include one or some other kind of detector. With its built in electronics it is really a minimum pulse rate detector.

What it is is a pulse rate generator, and rate threshold detector providing a binary output. The output switching capability is rather limited in current.

To test this you need a disk with an appropriate blob on its other surface and an appropriate variable speed drive to simulate an input signal.

.
 
gar said:
181108-2133 EDT

This device is not a prox switch, but it might include one or some other kind of detector. With its built in electronics it is really a minimum pulse rate detector.

What it is is a pulse rate generator, and rate threshold detector providing a binary output. The output switching capability is rather limited in current.

To test this you need a disk with an appropriate blob on its other surface and an appropriate variable speed drive to simulate an input signal.

.
Click to expand...


I would imagine the additional electronics makes it a bit more than $69.
 
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