Related Post

Protective RelayClassification or types of protective relaysCircuit Breaker Tripping SchemesThermal Relay

Index

SymbolsTransformerRelayPower-SystemBasic-electricalACSR-ConductorCircuit-BreakerInterview-questions-of-Basic-ElectricityInterview-questions-of-transformerInsulatorCurrent-TransformerMCQMCQ-powersystemThermal-power-stationInterview-questions-of-Power-SystemPower-ElectronicsInterview-questions-of-Underground-CableInterview-questions-of-IlluminationIlluminationMCQ-of-ElectronicsMCQ-of-Basic-ElectricalMCQ-of-Transformers MCQ-of-D.C-motor MCQ-of-D.C-generatorsMCQ-Control-SystemMCQ-Measurementsmcq-of-Generation-power-systemMCQ-of-Induction-MotorMCQ-of-Transmission-DistributionMCQ-of-Electrical-MachinesMCQ-of-Alternator-and-Synchronous-MotorsMCQ-Electric-Power

Protective Relay


≪ Previous Next ≫

A protective relay is a device which initiates the circuit breaker to cut the faulty circuit from the healthy system. It acts just like a ‘ silence guard’, when any fault occurred in a system, the relay operates to close the trip circuit of the breaker and the breaker disconnects the faulty circuit.

A typical relay circuit is shown in fig. There are three parts in the relay circuit :-

  1. First part is, the primary winding of a current transformer (C.T ) which is connected in series the line.
  2. Second part , secondary winding of C.T is connected in series with relay operating coil.
  3. Third part is the tripping circuit which may be either a.c and d.c . source of supply , trip coil of the circuit breaker and relay stationary contacts are connected in series connection.

Now describe , how the relay disconnects the faulty circuit . Suppose when a short circuit occurs at a point F, on the line , the huge current  flows in the line. Hence , a heavy current  flow through the relay coil, causing the relay to operate by closing its contacts. Result complete the tripping circuit of the breaker and making the circuit breaker open.




≪ Previous Next ≫


Related topics :


Recent Post

Multiple Choice Question (MCQ) of Materials page-6:
51. The permeability and permittivity of a medium are
A) independent of each other
B) related by the atomic number
C) related by the Boltzmann’s constant
D) related by the velocity of electromagnetic waves.

Read more...

Multiple Choice Question (MCQ) of Materials page-5:
41. Bakelite is
A) highly inflammable
B) low resistance conductor
C) a semi-conductor
D) uncombustible.

Read more...

Multiple Choice Question (MCQ) of Materials page-4:
31. Which of the following pairs is commonly used in thermocouples?
A) Copper-constant
B) Aluminium-tin
C) Iron-steel
D) Silver-German silver.

Read more...