Zinc Oxide Varistor

Varistors provide reliable and economical protection against high voltage transients and surges which may be produced, for example, by lightning, switching or electrical noise on AC or DC power lines. They have the advantage over transient suppressor diodes in as much as they can absorb much higher transient energies and can suppress positive and negative transients.
When a transient occurs, the varistor resistance changes from a very high stand-by value to a very low conducting value. The transient is thus absorbed and clamped to a safe level, protecting sensitive circuit components.Varistors are manufactured from a non-homogeneous material, giving a rectifying action at the contact points of
two particles. Many series and parallel connections determine the voltage rating and the current capability of the varistor.

• Wide voltage range selection – from 14 VRMS to 680 VRMS.
This allows easy selection of the correct component for
the specific application.
• High energy absorption capability with respect to size of
• Response time of less than 20 ns, clamping the transient
the instant it occurs.
• Low stand-by power – virtually no current is used in the
stand-by condition.
• Low capacitance values, making the varistors suitable for
the protection of digital switching circuitry.
• High body insulation – an ochre coating provides
protection up to 2500 V, preventing short circuits to
adjacent components or tracks.
• Available on tape with accurately defined dimensional
tolerances, making the varistors ideal for automatic
• Approved to UL 1449 edition 3 (file number: E332800) and
manufactured using UL approved flame retardant
• Completely non flammable, in accordance with IEC, even
under severe loading conditions.
• Non porous lacquer making the varistors safe for use in
humid or toxic environments. The lacquer is also resistant
to cleaning solvents in accordance with IEC 60068-2-45.