Thermal Relay Construction and Working Principle: Thermal Relay can operate on the principle of thermal effect of electric current. It consists of bimetallic strips which are used in small sizes and are heated by heating…
Permanent Magnet Moving Coil Relay: The arrangement of permanent magnet moving coil relay is shown in Fig. 9.12. In this relay, the coil is free to rotate in the magnetic field of a permanent magnet.…
Electromagnetic Induction Relay - Structure and Working Principle: Electromagnetic induction relay operate on the principle of induction motor and are widely used for protective relaying purposes involving a.c. quantities. They are not used with d.c.…
Classification of Relays: The protective relay may be defined as an electrical device interposed between the main circuit and the circuit breaker in such a manner that any abnormality in the circuit acts on the…
Types of Circuit Breaker Mounting: There are four types of circuit breaker mounting, which are described below: Cubicle Type or Cellular Type: In this type of mountings the circuit breakers and their ancillary equipment are…
HVDC Circuit Breakers - Construction and Working Principle: Light duty dc circuit breakers have been in use since long. However, there is lack of suitable circuit breakers for HVDC systems. At present most of the…
Difference between Fuse and Circuit Breaker: The difference between fuse and circuit breaker is given in table below S. No. Particulars Fuse Circuit Breaker 1 Functions It performs both of functions—detection as well as interruption.…
Factors to be Considered in Selection of Fuse: In order to ensure that the fuses will correctly and reliably protect any given section or element of an electrical circuit, selection of fuse characteristics and ratings…
Instrument Transformers - Definition, Types and Errors: AC type protective relays are actuated by current and voltage supplied by current and potential (or voltage) transformers, known as instrument transformers. The main function of instrument transformers…
Overlapping Zones of Protection: Overlapping Zones of Protection - In order to provide selectivity to the system it is usual practice to divide the entire system into several protection zones. When a fault occurs in…
