Widely used or not used by some people, Varistors are often seen as a black art by circuit designers, in laymans terms these units can be put across the supply rails of equipment they have a very high resistance at certain voltages and the voltages can be pre selected.

These units sit quietly not doing a lot in the circuit until they see the voltage rise above a set point at which time they very rapidly cut in and remove the
voltage spike, these units offer very fast response and current handling capabilities and are widely used in most home, office, and AC line clamping
in mains units, most voltage spikes are very high voltage, such as a close lightning strike for example but very short duration.

By fitting one of these units which can cost a few pence you can protect equipment from untold damage.

larger types are used where the duration of the spike may be more than transient in terms of a few pico seconds but more like micro seconds.

We are dealing with the Manufacturer directly and these parts form part of a larger range, in telecomm's and automotive, exact replacements for the Epcos range are available.

The code range indicates the body sizes, our web site links to the correct manufacturers data, samples available.