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

Strains are measured by strain gage elements, A rectangular rosette is moun...

A rectangular rosette is mounted on a test structure as shown, loads are applied, and the following strains are measured by strain gage elements 1, 2, and 3: ε 1 = 1500 μm/ m ε

Ferromagnetic substances , Ferromagnetic substances: on the basis of...

Ferromagnetic substances: on the basis of domain theory   A. 1. In a ferro magnetic substance, large no. of domains occur. 2. The direction of magnetisation with in a

Cyclic process of thermodynamic , When a system returns back to its initial...

When a system returns back to its initial state after passing by dissimilar phase, the phenomena is said to be a cyclic process. In this process as ΔU = 0. From first law of the

What is the effective voltage in the primary coil, A step-up transformer ha...

A step-up transformer has a primary coil having of 152 turns and a secondary coil with 3040 turns. The primary coil receives a peak voltage of 98 V. a. What is the effectiv

Discuss about the term graded index fibre, Discuss about the term graded in...

Discuss about the term graded index fibre. Graded index fibre: A graded index fibre is diverse from the step index fibre not merely in the core refractive index variation bu

Can you explain modulation, Can you explain modulation? Why is it required...

Can you explain modulation? Why is it required? What is "World Wide Web" (WWW)? Give the frequency range of speech signals.

Electrical Charge, if 36C of charge pass through a wire in 4 seconds what c...

if 36C of charge pass through a wire in 4 seconds what current is it carrying

What are the consequences of dispersion, What are the consequences of dispe...

What are the consequences of dispersion? The main familiar result of dispersion is the splitting up of the composite white light within its constituent colours as into a rainbo

Determine the acceleration of the car, While travelling in a straight line,...

While travelling in a straight line, a car uniformly alters its speed from 50 kilometres per hour to 110 kilometres per hour in 5 seconds.  The acceleration of the car during

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