The material used for fuse elements must be of low melting point, low ohmic loss, high conductivity (or low resistivity), low cost and free from detraction. The material used for making fuse element has a low melting point such as tin, lead, or zinc. A low melting point is, however, available with a high specific …
The fuse is a device used in an electrical circuit for protecting electrical devices against overloads and short circuit. It is the simplest and cheapest devices used for interrupting an electrical circuit under short circuit or excessive overload current magnitudes. It is used for overload or short circuit protection in high voltage up to 66 …
When the current across the contact of the circuit breaker is zero, a high-frequency transient voltage develops in the whole breaker contact and is produced by the sudden distribution of energy between the electric and magnetic field. This transient voltage is called restriking voltage. The voltage appears across the breaker contacts at the moment of …
Testing of circuit breakers is more difficult as compared to other electrical equipment like transformer or machine because the short circuit current is very large. Testing of the transformer is mainly divided into two groups, type tests, and routine tests. Type Tests of Circuit Breaker Type tests are conducted for the purpose of proving the …
In air break circuit breaker the arc is initiated and extinguish in substantially static air in which the arc moves. Such breakers are used for low voltages, generally up to 15KV and rupturing capacities of 500MVA. Air circuit breaker has several advantages over the oil, as an arc quenching medium. These are Elimination of risk …
Air blast circuit breaker used compressed air or gas as the arc interrupting medium. In the air blast, circuit breaker compressed air is stored in a tank and released through a nozzle to produce a high-velocity jet; this is used to extinguish the arc. Air blast circuit breakers are used for indoor services in the …
The HVDC circuit breaker is a switching device that interrupts the flow of abnormal direct current in the circuit. When the fault occurs in the system, the mechanical contacts of the circuit breaker are pulled apart and thus their circuit is open. In HVDC circuit breaker, circuit breaking is difficult because the current flow through …
The rating of the circuit breaker is given on the duties that are performed by it. For complete specification standard ratings and various tests of switches and circuit breakers may be consulted. Apart from the normal working of circuit breakers, the circuit breaker is required to perform following three major duties under short circuit conditions. …
A fixed connection of resistance in parallel with the contact space or arc is called the resistance switching. Resistance switching is employed in circuit breakers having a high post zero resistance of contact space. The resistance switching is mainly used for reducing the restriking voltage and the transient voltage surge. Severe voltage occurs in the system …
A breaker which used vacuum as an arc extinction medium is called a vacuum circuit breaker. In this circuit breaker, the fixed and moving contact is enclosed in a permanently sealed vacuum interrupter. The arc is extinct as the contacts are separated in high vacuum. It is mainly used for medium voltage ranging from 11 …
