If your Gems CAP-300 Series Capacitive Level Sensor is not performing as expected, please use the steps below to troubleshoot your sensor.

• Is the power supply correct? Standard sensors require a 9 to 32 VDC input.
• Is the wiring correct? Wiring schematics can be found in the bulletin on the product page

Double check that your wire colors/pinouts match correctly.

Orientation and Mounting

• The CAP-300 is designed to work in any orientation
• The black plastic tips should be kept at least 0.1” (2.5mm) away from any surface
• Is the CAP-300 probe tip fully exposed to the media, and not installed in a port or tube where media can get trapped?

Cleanliness

• Is the port/tip clean?
• Any dried-on debris that could cause a false reading?

Liquid/Media

• The CAP-300 relies on the Dielectric Constant (Dk) of your fluid in order to detect the difference between fluid present and no fluid present.
• The sensor switching threshold is factory set at a value of 30.
• Media with a Dk greater than 30 will be detected as “WET”. Conversely, media with a Dk less than 30 will be detected as “DRY”.

Some common Dk values:

Are you trying to detect foam? The CAP-300 was designed to ignore foam and will not detect it as wet.

Best Practices for Troubleshooting:

• Test with room temp tap water.
• This way, it is a good known target fluid.
• Remove the sensor completely from your mechanical and electrical system.
• This will isolate any variable in the circuitry.
• Use a known good power supply as well as a known good voltmeter and see if the sensor responds to water.

If these steps do not yield favorable results, please contact Gems via: Technical Support