Relationship between Voltage value and Type selection of varistor

The voltage protection effect of a varistor in an electronic circuit, usually allows electric shock with a current fuse or additional overvoltage protection. Working principle of varistor: voltage and current intensity of varistor identify special nonlinear relation. When the voltage applied on both sides of the varistor is lower than the nominal voltage, the resistance value of the varistor is close to infinity and the potential field flows through.

     Voltage sensitive resistance is a certain voltage limit protection within a certain voltage limit element, if blindly select high voltage sensitive voltage value, in the actual use of the situation does not have to produce such a high transient voltage. You don't get there. If the voltage is low, it will often live in working conditions, not only  it is the duration of the interference, some even burned out. Today, our 220V selection is 10K471. it is derived from the network potential difference of about 260V, and the maximum electric voltage is 1.414 / 260V / 368V. We can also estimate the value of our varistor by filling in the safety factor of root two, and in essence we can also estimate it by 2 to 3 times the normal voltage.