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

What is the standard calomel electrode? , The Saturated calomel electrode (...

The Saturated calomel electrode (SCE) is a reference electrode based on the reaction among elemental mercury & mercury (I) chloride. The aqueous phase in contact with the mercury a

Soecific heat capacity, A lead bullet moves horizontally with a velocity of...

A lead bullet moves horizontally with a velocity of 130 ms-1 and embedded into a cement wall after collision. If the specific heat capacity of lead = 130 JKg-1°C-1 and all heat pro

Explain power supply voltage, A diode in a circuit similar to the one in Fi...

A diode in a circuit similar to the one in Figure 29-26 has a voltage drop, V d , of  0.95 V when I = 18 mA. If a 390 Ω resistor, R, is connected in series, what power supply volta

Speed of center of oa just after collision, Two identical rods OA and OB ea...

Two identical rods OA and OB each of similar length and mass are connected by a massless pin connection, which permits rotation.The system is placed on a horizontal surface.Two mas

Explain history of nuclear reaction, Explain history of nuclear reaction? ...

Explain history of nuclear reaction? Bigger nucleus bust to from two lighter nucleus and two or three neutrons is known as nuclear fission used for making atom bomb two lighter

Motion in one dimension, a freely falling object near the Earth''s surface ...

a freely falling object near the Earth''s surface has constant?

Define strain, When deforming forces are applied to a body, there is a chan...

When deforming forces are applied to a body, there is a change in the size of the body. The object is known as strained or deformed. The ratio of change in dimension to the origina

Experiment of the path of a projectile, Path of a projectile The appara...

Path of a projectile The apparatus below can be used to indicate the independence of the horizontal and vertical velocities of a projectile. The projectile is a metal ball, and

Electrostatics, Can the whole charge of a body is transfer to another body

Can the whole charge of a body is transfer to another body

Newton'' ring, why dark spot appears on newton''s ring?

why dark spot appears on newton''s ring?

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