• Protocontrol Instruments (India) Private Limited

Zero/Under-Speed/Over-Speed Switch

Electronic speed switch, Series ESM, is used to monitor speed of conveyors, crushers, rolling mills, agitators, mixers, stirrers, screw conveyors, bucket elevators and other industrial machineries. The device actuates relay contacts at preset speed. Using these contacts, desired control action such as zero speed protection/under-speed protection/over-speed protection can be achieved.
Speed sensor is placed in close proximity of the rotating object. On this object, metallic plates are fixed. Sensor detects presence of metal objects which comes within the range of their oscillating field giving rise to corresponding pulses. These pulses are fed to the control unit where they are compared with the standard pulses to sense the speed. Output is in the form of relay contact. Standard contact rating is 5 Amp resistive at 230 V AC.
In case of under speed – zero speed application built-in initial by-pass time delay is provided to allow the rotating machinery to attend the desired speed. If after this set time the motor does not attend the set speed, the relay is de-energized and the switch resets automatically when the desired speed is attained. Speed range is to be selected considering normal running speed of the equipment and desired trip speed. Following models are available: ESM 1 W - Electronic Speed Switch for under speed monitoring, Field Mounting; ESM 2 W - Electronic Speed Switch with digital display, Field Mounting; ESM 4 W - Electronic Speed Switch for over speed monitoring, Field Mounting; ESM 1 F - Electronic Speed Switch for under speed monitoring, Flame proof Enclosure; ESM 1 D - Electronic Speed Switch with Digital display Front Panel Mounting; ESM 5 D - Electronic Speed Indicator (Tachometer) Front panel mounting.