Class 18 SMD Varistors

SMD varistors how they work A varistor is also known as a Voltage Dependent Resistor or VDR. The varistor function is a variable resistance depending on the voltage.
Varistors have no polarity, they are bidirectional.
This is class number 18 of the SMD Components.
Basically, the varistor has a nominal value, expressed in volts.
When the applied voltage exceeds this value, the varistor short-circuits.
In this way, it will prevent the current from passing through the rest of the components, avoiding damaging them. The varistors behave well with moderate voltage peaks and of very short duration. wear can end up damaging it.