What is a varistor used for?
Varistors are used to protect a circuit from high voltage surges. When a high voltage surge is applied to a circuit, the outcome is usually catastrophic to the circuit. A capacitor may be installed across the signal lines.
Is a varistor a surge protector?
Surge Protection In the most common type of surge protector, a component called a metal oxide varistor, or MOV, diverts the extra voltage. When voltage is below a certain level, the electrons in the semiconductors flow in such a way as to create a very high resistance.
How do you choose varistor voltage?
Choose a varistor with an energy absorption rating that equals or slightly exceeds the energy values associated with the event the circuit may experience. If, however, the transient voltage is due to an external event, the magnitude of the source energy is unknown.
Is the 7d471k MOV suitable for 220V application?
Many users ask us that MOV says marking as 470V so how is it suitable for 220V application. The AC mains you get said 220V RMS. So peak voltage is 308V = 220V x 1.4 (VPeak = VRMS × √2) This MOV 7D471K is having 300V AC RMS rating.
Why are varistors connected to surge arrester in series?
Varistors connected in series with the arrester are well suited for limiting the follow current To stop the arrester from responding during normal operation, a permissible tolerance of the line voltage of +10% and a possible derating of the arrester of –20% were taken into account.
What’s the peak voltage of a 220V varistor?
The AC mains you get said 220V RMS. So peak voltage is 308V = 220V x 1.4 (VPeak = VRMS × √2) This MOV 7D471K is having 300V AC RMS rating. So its suitable for 220V AC mains applications. Low Cost, Reliable, Easy to solder, No crystal needed, Few components needed.
How is a surge clamped in a series MOV?
A surge from line to neutral will be clamped by the series combination of the MOVs. A surge from either line or neutral to earth will be clamped by a single suppressor and the surge arrester to earth. The series MOV will also act to limit the current available to the arrester.
A varistor remains non-conductive as a shunt-mode device during normal operation when the voltage across it remains well below its “clamping voltage”, thus varistors are typically used for suppressing line voltage surges. Varistors can fail for either of two reasons.
What does a varistor do?
Definition: A varistor is a 2 terminal semiconductor device that protects the electrical and electronic devices from overvoltage transients. Its resistance is dependent on the applied input voltage. The word varistor is formed by the combining variable and resistor.
How does a varistor work?
This is how a varistor works in a circuit: When the voltage to a circuit is low or within acceptable limits, the varistor has a very high resistance. Since the varistor has such a high resistance, current does not flow through it; instead it flows to the device which needs power in the circuit.