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

Thin films, 2. Surface Crystallography and Epitaxy Fe thin films are grown...

2. Surface Crystallography and Epitaxy Fe thin films are grown on a single-crystal Al (100) substrate surface. The films grow with no dislocations (if they are thin enough) which

An aquarium for larger water animals, An aquarium for larger water animals ...

An aquarium for larger water animals A glass aquarium 50 cm by 25 cm is of useful size. Old accumulator cells are suitable, but the glass is not very obvious.  To prepare l

Semiconductor-motion of electrons, In a pure semiconductor, concentration o...

In a pure semiconductor, concentration of electrons in conduction band is equal to the concentration of holes in valence band. In the process of conduction when an electric field i

Calculate diameter of the ball, A ball is 6.5 m from a convex mirror with a...

A ball is 6.5 m from a convex mirror with a magnification of 0.75. If the image is 0.25 m in diameter. What is the diameter of the actual ball?

What are the properties of cathode rays, (i)Cathode waves always travel in ...

(i)Cathode waves always travel in straight path.   (ii) Cathode rays exert mechanical force on the objects they strike. (iii) Cathode rays make fluorescence. (iv)

Tangent law, State two conditions which must be satisfied in order to apply...

State two conditions which must be satisfied in order to apply tangent law in magnetism

#title.kinematics., what is the difference between diplacement and distance...

what is the difference between diplacement and distance

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

Calculate the capacitance of the capacitor, A parallel plate capacitor has ...

A parallel plate capacitor has nineteen interleaved plates each 75mm by 75mm separated by mica sheets 0.2mm thick. Assuming the relative permittivity of the mica is 5. Calcu

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