Explosion-proof electric motor - has ignition-protection pressure-tight encapsulation and uses semiconductor temp. sensors

摘要

An explosion proof electric motor esp. a three-phase motor uses ignition-protection type 'd' pressure - tight encapsulation. It is suitable for coolant range from approx. -60 deg.C up to more than 40 deg.C. It uses semiconductor temperature sensors as a primary protection against dangerously high motor housing surface temperatures occurring, such that ignition of gas-air mixtures is prevented when the motor is operated in explosion-hazardous surroundings. The temperature sensors also guard against excessively high bearing(s) temperatures occurring, and are connected together to a sensing-current circuit. Two groups of semiconductor temperature sensors built into the windings of the motor and connected to the sensing-current circuit are specif. used as a secondary or back-up protection to sense the temperature of the windings of the motor operating in an explosion-hazardous ambient, and to allow for fluctuations of the coolant-medium temperature.