Operating principle

The KPM KB2 operates on a proven, non-contact reflection principle. The light source can be

either RGB LED (red, green, blue) or IR LED (infrared). The optical sensor is placed above or under

the web. Applications include paper or board webs, wires or felts. Thanks to the unique RGB

detection method the color of the product or the felt has no effect on the measurement

reliability. The sensor is neither affected by dirt, steam nor temperatures up to 180 °C (356 °F)

when installed according to ABB Oy, KPM specifications. There are no electronic components

located in the sensor head.

The optical sensor is connected through a fiber optic cable to the RGB/IR light source located in

the display unit. The RGB/IR LEDs emit pulsed red, green, blue, or IR light onto the web surface.

The reflected light is received and transmitted through the fiber optic cable to the detector. All

light components are analyzed fast for a reliable break detection.

A break activates a relay, which can be connected to the logic control of a paper machine. The

reflected light intensities are also available as optional 4 – 20 mA analog outputs.

The self-cleaning sensor head is a 33.7 x 1500 mm (1″ x 59″) stainless steel tube with two holes

serving as eyelets for the fiber optics and outlets for purge air. Continuous airflow through the

stainless steel enclosure keeps positive pressure around the sensor head’s eyes and keeps the

eyelets free of steam, dust or debris. The openings should be located towards the surface being

monitored.