Surge protector electrical symbols are generally expressed in SPD, as shown in figure: Surge suppressor is the role of high voltage spike suppression contactor disconnect moment caused by coil back emf. Reduce the image of other electronic circuits.
To avoid AC contactor disconnect instantaneous reverse potential, that is, both ends of the coil and resistance capacitance absorption loop.
Different capacity, coil voltage contactor, its resistance capacitance absorption value is different.
Inductive circuit turn on and off the meeting caused by excessive voltage, especially in the case when the contactor control loop disconnect occurs. Disconnect the contactor coil when the coil leads to closed loop stored in the magnetic current in the electromagnetic energy release, with a voltage wave characteristic of amplitude recovery, steep and high, up to kV, this situation seriously interfere with the electronic equipment caused by insulation burned, destroyed the sensitive device. In order to reduce the harm that manufacturers design the special surge suppressor; can reduce or inhibit pre damping conditions and expected high frequency correlation.
Methods: diodes, adjustable resistance, adjustable resistance RC device, RC device are respectively connected with the coils in parallel.

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