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What is generator varistor?
A varistor is an electronic component with an electrical resistance that varies with the applied voltage. When used as protection devices, they shunt the current created by the excessive voltage away from sensitive components when triggered. The name varistor is a portmanteau of varying resistor.
What is the use of varistor in alternator?
As per data available on internet the Varistor protect the electronic component from Transient Voltage or surge in voltage or lightning strike. in these condition the varistor internal resistance become low & it create close path which will protect the components.
How to select the right varistors For overvoltage circuit?
1 Circuit conditions such as the peak voltage and current during the surge event 2 The MOV continuous operating voltage (should be at 20% above maximum system voltage under normal conditions) 3 The number of surges the MOV must survive 4 Acceptable let-through voltage for the protected circuit
How are varistors used in voltage dependent diodes?
Zener—or avalanche diodes—and voltage-dependent resistors (varistors) display a variable impedance, depending on the current flowing through the device or the voltage across its terminals. They use this property to clamp the overvoltage to a level dependent on the design and construction of the device.
How are varistors used to protect against transients?
However, if the varistor is expected to protect against transients originating from external sources, the magnitude of the transient is typically unknown and an approximation technique must be applied. This involves calculating the energy absorbed after finding the transient current and voltage applied to the varistor.
Why do we need varistors for surge protection?
As such, a growing number of varistor-based surge-protection devices offer a built-in thermal disconnect function. It provides added protection from catastrophic failures and fire hazards, even under extreme circumstances of varistor end-of-life or sustained overvoltage.