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

Magnetic Field, Consider a circular loop in a magnetic field. The loop is m...

Consider a circular loop in a magnetic field. The loop is made of elastic material with spring constant k. It carries a current I and has radius R when unstretched. We immerse it i

Is stone take longer for the downward motion, Is stone take longer for the ...

Is stone take longer for the downward motion than for the upward motion Consider a stone thrown vertically upward. if we take friction against air into account, we see that the

Explain quasi-static process and isothermal process, Explain quasi-static p...

Explain quasi-static process The process in the system the variables (PTV) alters very slowly so that the systems remain in thermal and mechanical equilibrium with its surround

What instrument is used to measure volume, What instrument is used to measu...

What instrument is used to measure volume? Liquid volume is calculated with beakers, measuring cups, spoons, graduated cylinders, and the like. For regular objects, solid volum

Projectile motion, If a ball thrown horizontally with a velocity of 20m/s f...

If a ball thrown horizontally with a velocity of 20m/s from a tower meters high, after how long will it strike the ground?

What is the accuracy in the determined value of g, The length of a simple p...

The length of a simple pendulum is about 100cm known to have a accuracy of 1mm.Its period of oscillation is 2s determined by measuring the time for 100oscillations using a clock of

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

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