Voltage dependent resistor, Physics

Assignment Help:

A VDR is a special type of resistor that changes its resistance with rise in voltage. It has a very high resistance at low voltage (below the trigger voltage) and very low resistance at high voltage (above the trigger voltage). It is also called varistor or voltage sensitive resistor. There are two types of varistor.

SILICON CARBIDE VARISTOR:-              

MANUFACTURING: These are made up of silicon carbide. It is milled and mixed with a suitable ceramic binder. Then it pressed and extruded to desired shape of disc, rod or washer. Then it is sintered under controlled temperature to produce hard material. Wire leads are then connected.

METAL-OXIDE VARISTOR (MOV):

MANUFACTURING:

 Zinc oxide and bismuth oxides are mixed with other powdered metal additives, pressed into discs and sintered at 12000C. It has an encapsulated polycrystalline ceramic body; with metal contacts and wire leads.

APPLICATIONS: A varistor acts as a switch. It is usually used for short circuit protection in power strips or lightning bolts "arrestors" on street power poles. It is also used as a "snobbier" in inductive circuits.

 


Related Discussions:- Voltage dependent resistor

Who discovered proton, Who discovered Proton? In 1886 Eugen Goldstein d...

Who discovered Proton? In 1886 Eugen Goldstein discovered canal rays (also called as anode rays) and showed that they were positively charged particles (ions) formed from gases

Write the expression for equivalent focal length, What occures to the norma...

What occures to the normal shift when the thickness of the optical medium is decreased? Write down the expression for equivalent focal length of combination of two thin lenses d

Newton''s rings, why we take large radius of curvature of lens

why we take large radius of curvature of lens

How much percent conductivity of copper is less than silver, The conductivi...

The conductivity of copper is less than that of silver by (A) 5 - 10 %. (B) 50 - 60 %. (C) 80 - 90 %. (D) 20 - 30 %. Ans: The conductivity of copper

Einstein relations by upward and downward transition, Determine the Einstei...

Determine the Einstein relations by upward and downward transition. While the system is in equilibrium, the upward and downward transition rates should be equal. N 1 ρ(ν) B

Velocity, initial acceleration rocket is 0.01t in upward dirction initioal ...

initial acceleration rocket is 0.01t in upward dirction initioal velocity is 50ms-1 , what is the function for the velocity of the rocket?

Why ferrite core has less eddy current loss than iron core, A ferrite core ...

A ferrite core has less eddy current loss than an iron core because ferrites have (A) High resistance. (C) Low permeability. (B) Low resistance. (D) High hyster

What is the ohm law, What is the Ohm Law? Ohm discovered that the amoun...

What is the Ohm Law? Ohm discovered that the amount of current was directly proportional to the voltage (more voltage gives more current) and inversely proportional to the resi

Determine the characteristics of the filter, 1. We want to measure a sinuso...

1. We want to measure a sinusoidal signal (frequency 100 Hz) expected to be of strength 1 mV RMS in the presence of noise of peak amplitude 3 mV.   (a) If our A/D converter has

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd