Measures for the protection of explosion-proof electric valves varying load equipment

In the past for motor protection method is to use a fuse, overcurrent relay, thermal relay, thermostat, etc. , but these methods all have advantages and disadvantages. The variable load of explosion-proof electric valve device, is not absolutely reliable measures for the protection of. So we must take various combinations, induces has two kinds: one is the increase or decrease of the motor input current judgment; The second is the motor itself heating situations. These two approaches, both the heat capacity of the given time allowance to consider motor. Electric gate valves, electric valve explosion-proof electric three-way ball valve, usually on the basis of the overload protection method is: the continuous operation of motor or inching operation over load protection, use a thermostat; The protection of motor blocked, the thermal relay; For short circuit accident, adopt the fuse or over-current relay. Late due to the innovation of system development, domestic explosion-proof electric valve without big technology innovation, poor controllability and low measurement precision, large amount of maintenance, etc. At present there are 20 of explosion-proof electric valve in use - 250000 units have been in the stage of change. And the original domestic explosion-proof electric valve has to replace. Domestic explosion-proof electric valve mechanical life in 15 - 25 years, motor life 8 - For 10 years. In addition, there are 3 - Explosion-proof electric valve electric control part of the 50000 sets of import have different problems need to be solved.