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

Screw gauge, 1. A screw gauge consists of U- shaped metallic frame F. To on...

1. A screw gauge consists of U- shaped metallic frame F. To one end of this frame, a flat shaft is fixed. On the opposite end of a hollow long cylinder C is fixed. 2. The hollow c

What is modern view, What is Modern view Modern view : It objects tend...

What is Modern view Modern view : It objects tend to remain in their initial state; force is needed to change motion. Resistance to alters in motion is known as inertia.

Compound microscope, What is the principle and ray diagram of a compound mi...

What is the principle and ray diagram of a compound microscope

Compute the flux through the coil, Q. A coil of area of cross section 0.5 m...

Q. A coil of area of cross section 0.5 m 2 among 10 turns is in a plane perpendicular to a magnetic field of 0.2 wb / m 2 . Compute the flux through the coil.

Illustrate the waveform of output voltage, For circuit demonstrated in figu...

For circuit demonstrated in figure, draw waveform of output voltage V O . Suppose ideal diode D and lossless capacitor C. Name of the circuit given in figure is Positive C

Determine the power absorbed by the circuit, A 20 Ω non-reactive resistor i...

A 20 Ω non-reactive resistor is connected in series with a coil of inductance 80mH and negligible resistance. The combined circuit is connected to a 200V, 50Hz supply. Calcula

Astrophysics question, consider a star orbitining in the sperically graviat...

consider a star orbitining in the sperically graviational potential Y=(Vc)2 ln(r/r0). a)use conservation of energy and angular momentum to obtain equation for dr/dt and d(teta)/dt

What is thermal neutrons, Fast neutrons can be changed into slow neutrons b...

Fast neutrons can be changed into slow neutrons by certain materials known as moderator's  when last moving neutrons pass by a moderator, they combine with the molecules of the mod

Temperature joule, Temperature joule; J (after J.P. Joule, 1818-1889) ...

Temperature joule; J (after J.P. Joule, 1818-1889) The derived SI unit of energy described as the amount of work done by moving an object by a distance of 1 m by applying a fo

What is randomized common ends, What is randomized common ends? When so...

What is randomized common ends? When some light guides are bundled together in a single common end this becomes a physical impossibility to get the same level of light in each

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