It is on the motor for a mud pump on a directional drill. The drill has a water flow meter and a reostat knop for adjusting flow. Is this a rpm sensor for the meter or could it be some kind if actuator to control pump pressure? Or something else? It had 3 wires going to it. Thanks for reading.
With the locknut it looks very much like a speed sensor. If you remove it (make sure to maintain the adjustment) I’ll bet there is a gear of some sort directly underneath the sensor nose.
Thank you. That's what I was thinking.
Definitely a speed sensor.
Unplug it and you'll find out
Speed sensor. Three wire means it’s an active powered sensor, Hall effect type I’m guessing instead of the two wire passive magnetic pickup.
I found the diagram for it. My fluid meter display is broken. Any chance this sensor puts out a 0-12v signal so I could just use a multimeter to monitor it while waiting for a new one.
I would’ve thought the output of that sensor would be a square waveform of some sort
I want to say no. Something’s sitting in the back of my memory saying these sensors have a constant duty cycle unlike a PWM position sensor.
It's akin to a car Wheel Speed Sensor. On a car, if I connect a multimeter set to AC, the millivolts output rises the faster that I spin the wheel. It is essentially a square wave. I believe the technical term is a "Hall Effect" sensor?
It is a "Hall Effect" pickup. The rise and decay of the output pulse is too fast to see on a multimeter but an oscilloscope shows a true representation of the output signal. Passed through a comparator circuit the actual speed of the rotating shaft can be determined. Most multimeters are average responding and this is a blend, or homogenous display of the actual waveform; basically a representation. This can be useful in itself if a "look up" table has been created to use this data in a useful format. Basically a shaft speed could be 1800rpm and the output average output voltage be 12VDC. If the shaft rpm is arbitrarily increased, or decreased, this average voltage display/reading will either increase, or decrease. This data incorporated, and interpreted correctly can be a very valuable tool to even the most novice of troubleshooter.
I got a new display for the "water flow meter" and the sensor works. You can set up display to either count up or show rpms. I use it in rpm mode.
Hall Effect is an on/off and can be tested if you can rotate it manually. With a meter it will jump from showing zero volts to your reference voltage fed into it coming out of the output wire.