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

How will you change the galvanometer into an ammeter, A galvanometer with a...

A galvanometer with a coil of resistance 120 ohm shows full scale deflection for a current of 2.5 mA. How will you change the galvanometer into an ammeter of range 0 to 7.5 A? Veri

Gravitation- numerical probelm, A ball dropped from a balloon at rest clear...

A ball dropped from a balloon at rest clears a tower  81m high during the last quater second of its journey. Find the height of the balloon and the velocity of the body when it rea

Define electric circuits, Define Electric Circuits So far we have only ...

Define Electric Circuits So far we have only looked at electric charges sitting still and static discharges (like a shock or lightning). When we count on the charges moving thr

Schrodinger Equation, For what purpose do we use Schrodinger equation in ou...

For what purpose do we use Schrodinger equation in our daily life?

What is potential gradient, What is Potential Gradient Magnitude of ele...

What is Potential Gradient Magnitude of electric field at a point on an equipotential surface equal's rate of alter of potential, ΔV, with distance Δx, as point moves perpendic

Electricity, is it the current or the voltage which is responsible for elec...

is it the current or the voltage which is responsible for electrc shock?

How are amps and watts related, How are amps and watts related? In a nu...

How are amps and watts related? In a nutshell, the power (measured in watts) dissipated by a resistance is directly proportional to the square of the current (measured in amper

Determine the half-value layer of photons in air, Determine the HVL of phot...

Determine the HVL of photons in air, water, muscle, bone, and Pb for energies of 5 keV, 100 keV, 1 Mev and 100 MeV and then fill in the table below. Note that you must find the HVL

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