Capacitive Proximity Switch

Capacitive Proximity Switches are designed for sensing a wide range of materials. These switches give a superior performance for detection of various non-metallic objects where the Inductive type switches cannot function.

The major applications of Capacitive Switches include sensing of

Liquid Level

Plastic granules & Parts

Sand / Bulk Material Level

Food / Grain / Confectionary

Paper & Rubber

Glass Bottles / Tins in Packaging

WORKING PRINCIPLE
The switch works on the principle of a resonant oscillating circuit. A pair of brass/copper disc form the electrodes of a capacitor & the object acts as a dielectric media. The change in capacitance value, due to the presence of an object, is sensed by a precision integrated circuit. An effective output signal is generated at a preset value of capacitance.

CONSTRUCTION
These are offered in tubular threaded housing from size
M18 to M80. The enclosures are made of Brass, Stainless Steel or Engineering Plastics. Special shapes, Teflon housings are provided against requirements. Standard models are provided with an integrated 2-meter long cable. Connector type versions are available with built-in male connectors.

SENSING DISTANCE
The nominal sensing distance of any size of the switch is specified with Water as a standard object and tested at 25 Degree C. Depending upon the material of the object to be detected, the distance will vary. The sensitivity of the sensor is adjustable with a trimpot provided usually on the rear side of the sensor.

EFFECT OF AMBIENT CONDITIONS ON SENSITIVITY
The sensing distance is affected by the change in ambient temperature, humidity, size and material of the object.

SPECIAL MODELS
Special High-Temperature models of Capacitive switches are available with Operating Temperature up to 150 degrees C max.
These switches are provided with a Teflon front cap and with suitable Teflon cable.
These switches are to be used with a specially designed controller/amplifier unit.
The permitted operating length between a sensor and the controller is maximum 10 meters.
NAMUR type switches are available with CMRI-Certificate and approved Power Supply Unit with built-in Zener barrier circuit.

PROTECTIONS
All the Capacitive switches are provided with Reverse polarity, Overload, short circuit and false pulse protections.
Rugged construction along with the IP-67 grade of protection renders these switches to be very useful for liquid level monitoring applications.