METAL
OXIDE VARISTOR
CHARACTERISTICS AND FUNCTION
INTRODUCTION 

JNR ZINC
OXIDE VARISTORS 
Zinc oxide varistor is a voltage
dependent resistor with symmetrical voltagecurrent characteristics that is designed to
protect all kinds of electronic devices or elements from switching and induced lightening
surges. It's non linear exponent characteristic with broad using range and mass production
is gradually being used by various level of electric engineering. 
FEATURES 
 Fast response time.
 Low leakage current.
 Excellent voltage & energy ration.
 Low standby power and no follow on current.
 High performance in surge current handing capability.
 High performance in clamping voltage characteristics.

APPLICATIONS 
 IC, diode, transistor, thyristor, triac, and other
semiconductor protection.
 Suppression of mainborne transients in consumer electronics
and industrial electronics.
 Suppression of internally generated spikes in electronics
circuit.
 Surge protection in, communication, measuring and controller
electronics.
 Surge protection in electronic home appliances and gas and
petroleum appliances.
 Relay and electromagetic valve surge absorption.

PARAMENTERS
DEFINITION 
 Varistor Voltage (breakdown voltage):
The varistor voltage is the voltage across the varistor measured at a specified current
IC(0.1mA or 1mA) of specified duration.
 Maximum allowable voltage:
The Maximum allowable voltage corresponds to the rest state of the varistor. The rest
state voltage offers a low leakage current in order to limit the power consumption of the
protected device and not to disturb the circuit to be protected.
 Non linear exponent (£\ ):
The varistor voltagecurrent characteristic is defined by the equation:
I=KV^{£\} where
K is a constant dependent on geometry, and is the non linear exponent. We usually
take two points(V1,
I1)(V2, I2) to estimate the of £\
.

£\= 
log I1/I2 

In which, and I2 are the current value 



log V1/V2 

corresponding to the voltage
value V1 and V2 

 Maximum clamping voltage:
Maximum clamping voltage is the maximum voltage Vp between two terminals with the
specified standard impulse current I (8x20 µ sec.). The voltage value is an indication on the protective
function of the varistor.

HOW TO ORDER
PART DIMENSIONS
