The varistor is a voltage limiting maintenance device. Using the nonlinear characteristics of the varistor, when overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value, and then complete the maintenance of the subsequent circuit.

We mainly introduce the use and effect of varistors in micromotors.

The use of varistors in micromotors is primarily to absorb the reverse electromotive force of the motor during commutation. Avoid sparks on the commutator pole when the commutator is short circuited, so as to burn the commutator and brush surface due to high temperature, affect the service life of the motor, generate electromagnetic waves, and interfere with the use of other electronic products.

The principle of varistor: varistor, literally, is understood to be sensitive to voltage and change. With the increase of its top voltage, its resistance value can change from the level of M Ω (megohm) to the level of M Ω milliohm. When the voltage is low, the varistor works in the leakage current area, showing large resistance and small leakage current. When the voltage increases to the nonlinear region and the current changes in a large range, the voltage changes very little, and presents a good voltage constraint characteristics.

When the voltage rises again, the varistor enters the full area and presents a smaller linear resistance. Because of the large current, the varistor will overheat, burn or even burst with the passage of time. The varistor is usually in the current leakage area and enters the non-linear area to release the surge current when subjected to the surge impact. Usually, it cannot enter the full area.

Selection of the varistor in the motor: The selection of the varistor is usually the nominal voltage E1, which is the voltage value between the two ends when the varistor flows 1mA current.

Source: Jiangmen DC Motor Wholesale www.jmchiyang.com