Frequently Asked Questions

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Capacitance Sensors

How does a CAP 100, 200 work?

Answer: There are two electrodes which are coupled together and integrated into a high frequency oscillator. When there is no dielectric material (the dielectric material is what is being sensed) the oscillator is tuned to be in the resting state. As a dielectric material enters the electric field of the sensor, the capacitance increases and oscillation begins. When the amplitude of oscillation reaches a high enough level, a change in signal state is triggered.

Standard catalog part numbers are NPN sinking devices but PNP Sourcing available on request.

Which CAP sensors are Nonintrusive sensors?

CAP-100 or CAP-150 family is suited for detecting through a plastic or glass tank and is not intrusive.

Which CAP sensor must touch the liquid media?

The CAP-200 is suited for contact detection of liquids and must touch the media via a ½” NPT half coupling mounted to the side of the vessel. For metal tanks a shielded sensor is required.

What is the best way to position the CAP Sensor and can it be mounted on the bottom of the tank?

Mounting the CAP sensor on the side of the tank is the best way to detect media level. Mounting on the bottom of the tank may give undesirable results and should be thoroughly tested as it is difficult to sense a thickness of the media. A slight film or droplets of media on the bottom surface of the tank may trigger the CAP. The set point can be tricky.

What other ways can the CAP 100 be mounted if not using the mounting holes?

You can use a plastic tie wrap or double sided tape. For double sided tape, it is preferable to mount it over the bulls eye to minimize the gap between the sensor and the container. Glue is not recommended as the sensor will detect the glue.

When should I use a shielded CAP sensor?

It should be used for non-conductive medias and when mounting the CAP sensor on a metal bracket or metal mounting plate.

When should I use an unshielded CAP sensor?

They are used for conductive medias and cannot be mounted on metal brackets or metal surfaces.

Will CAP sensors be affected by humidity or moisture?

Yes, humidity or moisture on the sensor face can make the sensor unstable. Liquid droplets on the sensor face can cause the unit to become unstable. As a side note, dust and moisture have less of an effect on unshielded sensor than on shielded sensors.

Can the CAP sensor be calibrated in the factory?

Yes, factory calibration is available for large volume OEM applications. Call the factory for details.

For non-OEM users, you must calibrate the CAP in the application with your media. Also be sure to turn the calibration pot ¼ to ½ turn past the point that the indicator light comes on as an added safety factor. Instructions will be supplied with each sensor.

When would recalibration be necessary for CAP sensors?

Changes in Sensor or bottle position, bottle wall thickness, or fluid dielectric fluctuations can impair capacitance sensor performance and recalibration becomes necessary.

How do I reset the CAP sensor back to the factory setting?

The CAP sensor has a 40-turn pot clutched. To set it back to the factory setting, turn the pot all the way to the end, then turn it back 20 turns. Then you should be ready to recalibrate in your application per instructions provided in the originally bulletin that came with the sensor

When mounting more than one shielded CAP sensors, how much space do you need between them?

When two shielded sensors are mounted side by side, the minimum distance between them must be greater than one time their width.

When mounting more than one unshielded CAP sensors, how much space do you need between them?

When two unshielded sensors are mounted side by side, the distance between them should be at least four times their width.

When mounting more than one shielded or unshielded CAP sensors, how much space do you need between them if you want to mount them face to face?

When two shielded or unshielded sensors are facing each other, they must be mounted eight times the housing diameter or width away from each other.

What is the MTBF for CAP-100?

The MTBF is 782,472.61 hours.

What approvals do the CAP-100 & CAP-200 have?

CE approved ED Directives: 2006/95/EC-2004/108/EC Standards: EN 61000-4-3, EN 61000-4-20 Certification documents available upon request.

Can more than 1 CAP sensor be wired in parallel or series?
No, Multiple CAP sensor outputs should not be connected in parallel or series. This is a limitation of the output driver circuit in these sensors.
What is the diode part number that is referenced for inductive loads per the wiring diagram for a Cap-300?
Reference Diode part# 1N4004, (400V peak input voltage)
When would a diode be used?
It must be used for inductive loads, wired cathode to positive.
CAP-200 – the input voltage is 6-48 VDC. What would happen if I used 5 VDC?
We specify 6-48VDC due to the voltage regulator. If you use 5VDC the voltage will not be regulated and you would have to make sure it stayed at a constant 5VDC. If the voltage changed in any way, it would have to be reset by recalibrating the sensor. Due to this, we do not recommend 5VDC.