This component is also known as a voltage dependent resistor and has a nonlinear, non ohmic current voltage characteristic that is similar to that of a diode. In contrast to a diode however, it has the same characteristic for both directions of traversing current. At low voltage it has high electrical resistance which decreases as the voltage is raised. Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltages. When used as protective devices they shunt the current created by the excessive voltage away from sensitive components. This can cause them to blow and they will therefore need to be replaced in order to protect the more expensive sensitive component.
Characteristics of the 450-11760-1 Varistor Blue
The most common type of varistor is the metal-oxide varistor which contains a ceramic mass of zinc oxide grains in a matrix of other metal oxides which could be small amounts of bismuth, cobalt or manganese. This is sandwiched between two metal plates which are the electrodes. The boundary between each grain and its neighbour forms a diode junction which allows current to flow in only one direction. The mass of randomly oriented grains is electrically equivalent to a network of back to back diode pairs, each pair in parallel with many other pairs. The unit remains non-conductive as a shunt mode device during normal operation when the voltage across it remains well below its clamping voltage. This makes them ideally suited for suppressing line voltage surges.
Specifications of the Varistor Blue
To replace a blown varistor you first need to read the information printed on it or use the colour codes to ascertain the voltage parameters. They will denote the varistor’s energy rating in joules as well as the operating voltage, response time, maximum current and breakdown or clamping voltage. These are all important to the correct functioning of the circuit and fitting the wrong capacity varistor could cause the unit to malfunction or the resistor to fail to protect the sensitive component. Order from Generator Parts today.