The application of protective measures for motor products can not only ensure the long-term stability of the motor, but also effectively protect the safety of personal property. The protection link is an indispensable part of all automatic control systems, such as three-phase asynchronous motors, torque motors and other products, will add short-circuit protection measures, so the following and Senli motor Xiaobian together with a simple understanding of it.

       1.Short circuit protection

       Three-phase asynchronous motor, torque motor and other products of winding and wire insulation damage, control electrical and line damage, misoperation and line collision caused by line short circuit fault, with protection electrical quickly cut off power measures for short circuit protection.

       Commonly used short-circuit protection appliances are fuses and automatic air circuit breakers. The commonly used short-circuit protection elements are fuses and circuit breakers. The melt of the fuse is in series in the circuit to be protected, and when the circuit is short-circuited or seriously overloaded, it automatically fuses, thus cutting off the circuit to achieve the purpose of protection.

       2.Undervoltage protection

       When the grid voltage is reduced, the motor will operate under voltage. On account ofThree-phase asynchronous motorThe load does not change, so the motor torque decreases under undervoltage, the stator winding current increases, affecting the normal operation of the motor or even damage the motor, at this time, the protection appliance is used to cut off the power supply for undervoltage protection.

       3.No-voltage protection

       When the production machinery is working, the power grid suddenly fails for some reason, and when the power supply is restored, the protection electrical appliances must ensure that the production machinery can be restarted before operation, and will not cause personal and equipment accidents. This protection is the loss of voltage (zero voltage) protection. The appliances that achieve no-voltage (zero voltage) protection are contactors and intermediate relays.

       4.Weak magnetic protection

       The use of protective appliances to ensure that the DC motor works under a certain strength of the magnetic field, will not cause the magnetic field to weaken or disappear, to avoid the motor speed rise rapidly, and even the phenomenon of speed, this protection is weak magnetic protection.

       5.Overload protection

       When the three-phase asynchronous motor, brake motor and other products, the load is too large, the starting operation is frequent or the phase is missing, the working current of the motor will exceed its rated current for a long time, resulting in the motor life shortening or damage. When the motor is overloaded, the measure of cutting off the power with the protective electrical appliance is overload protection.

       6.Overcurrent protection

       Use protective appliances to limit the starting current or braking current of the motor, so that the motor runs under the safe current value, without causing damage to the motor or mechanical equipment, such protection is overcurrent protection. The method of implementing overcurrent protection: the coil of the electromagnetic overcurrent relay is connected in series in the main circuit, and the normally closed contact is connected in series in the control circuit; When the over-current value of the motor reaches the action value of the over-current relay, the normally closed contact disconnects the control circuit, and makes the motor stop from the power supply, thus realizing the over-current protection.

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