How to read varistor code

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MOVs or metal oxide varistors are devices designed for controlling mains switch ON surges in electrical and electronic circuits. Selecting an MOV for a particular electronic circuit might require some consideration and calculation, let's learn the procedures here. Metal oxide varistors or simply varistors are non-linear surge suppressor devices which are used for suppressing sudden, high abnormal voltage transients or surges, especially during power switch ON or thunder lightening situations. These are mostly used in sensitive electronic circuits for safeguarding against such catastrophic occurrences. MOVs are basically non-polar, voltage dependent devices, meaning these devices will react to changes in voltage conditions. Therefore MOVs are specified to trigger ON whenever the rated magnitude of voltage across their connections is exceeded.

How to read varistor code

Welcome, Guest. Please login or register. Did you miss your activation email? This topic This board Entire forum Google Bing. Print Search. Pages: [ 1 ] Go Down. Author Topic: Old varistor code interpretation Read times. RickEev Newbie Posts: 5 Country:. See photo. I assume this is not a "good thing" and plan to replace them, but with what?

Residual voltage ratio : When the current flowing through the varistor is a certain value, the voltage generated across it is called this current value as the residual voltage.

A varistor is a device with a non-linear volt-ampere characteristic. It is mainly used to clamp the voltage when the circuit is subjected to overvoltage and absorb excess current to protect sensitive devices. The material of the resistor body of a varistor is a semiconductor , so it is a variety of semiconductor resistors. The "zinc oxide" ZnO varistor, which is now widely used, has the main material composed of the divalent element zinc Zn and the hexavalent element oxygen O. So from the perspective of materials, the zinc oxide varistor is a kind of "II-VI oxide semiconductor". A varistor. A varistor is a voltage-limited protection device.

Unlike the fuse or circuit breaker which offers over-current protection, the varistor provides over-voltage protection by means of voltage-clamping in a similar way to the zener diode. But unlike a variable resistor whose resistance value can be manually varied between its minimum and maximum values, the varistor changes its resistance value automatically with the change in voltage across it making it a voltage-dependant, non-linear resistor or VDR for short. Nowadays the resistive body of a varistor is made from semiconductor material making it a type of semiconductor resistor with a non-ohmic symmetrical voltage and current characteristics suitable for both AC and DC voltage applications. In many ways the varistor looks similar in size and design to a capacitor and is often confused as being one. However, a capacitor cannot suppress voltage surges in the same way a varistor can. When a high voltage surge is applied to a circuit, the outcome is usually catastrophic to the circuit, therefore the varistor plays an important role in the protection of delicate electronic circuits from switching spikes and over voltage transients. Transient surges originate from a variety of electrical circuits and sources regardless of whether they operate from an AC or DC supply as they are often generated within the circuit itself or transmitted into the circuit from external sources. Transients within a circuit can rise rapidly increasing the voltage to several thousand volts, and it is these voltage spikes which must be prevented from appearing across delicate electronic circuits and components. Varistors are connected in circuits across a mains supply either phase-to-neutral, phase-to-phase for AC operation, or positive-to-negative for DC operation and have a voltage rating to suit their application. A varistor can also be used for DC voltage stabilization and especially for electronic circuit protection against over voltage pulses.

How to read varistor code

A varistor is a device with a non-linear volt-ampere characteristic. It is mainly used to clamp the voltage when the circuit is subjected to overvoltage and absorb excess current to protect sensitive devices. The material of the resistor body of a varistor is a semiconductor , so it is a variety of semiconductor resistors. The "zinc oxide" ZnO varistor, which is now widely used, has the main material composed of the divalent element zinc Zn and the hexavalent element oxygen O. So from the perspective of materials, the zinc oxide varistor is a kind of "II-VI oxide semiconductor". A varistor. A varistor is a voltage-limited protection device.

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The static capacitance refers to the inherent capacitance of the varistor itself. But it differs from the diode as it has identical features for its directions left and right sides of traversing voltage. It does not mean the varistor failed unless moisture got in. A varistor. But, if the resistance reads nearly infinite, it means that the varistor is in good condition. I got those MOV values from the board. Thank you for your extremely informative and to the point articles and advice. Are you unfamiliar with the term? With that in mind, you can say that a high voltage surge could happen when you switch off an inductive circuit. Leader LBO sch clipping. There are three types of photoresistor: ultraviolet photoresistors, infrared photoresistors, visible light photoresistors. That is, the device should read resistance times ohms.

The small package of resistance, the resistor is used in so many circuits, in so many forms, that it is almost an omnipresent electric component. From the very basic fixed resistors, where the resistance remains unchanged, to different types of variable resistors, whose resistances change according to different factors.

Dear Swagatam, I have been following you since quite some time on your website. Are you unfamiliar with the term? EEVblog on Youtube. I can read on the green-coloured Varistor a few numbers and letters: NR and Sp and like 73 or 76 or 78, it is about 15mm dia and 5. It's confusing you have another thread in repair on this. When the voltage applied to the varistor is lower than its threshold value, the current flowing through it is extremely small, which is equivalent to a resistor with infinite resistance, vice versa. A resistor is the most numerous component in electrical equipment, but it is not the component with the highest damage rate. Also, you can compare the extensive network of diodes in parallel and series to the matrix of erratically oriented grains. Can you help me out here? These are mostly used in sensitive electronic circuits for safeguarding against such catastrophic occurrences. And since the above reaction is sudden, MOVs are characterized as non-linear devices, which implies that these will not vary their characteristics gradually but suddenly when the specified parameters is exceeded. With that in mind, you can say that a high voltage surge could happen when you switch off an inductive circuit. The structure of a typical metal oxide varistor is as follows:. I have luminous shakti charge inverter Please tell me which MOV to be used in input line or ele. However, metal oxide varistors can be used for a variety of varistor voltages, from about 10 volts to more than volts AC or DC, so it can help you choose by knowing the supply voltage.