Working principle of magnetic relay and the circuit breaker

Magnetic Relay:

A magnetic relay is an electrical switch that uses a magnetic coil to operate a set of contacts. It is a type of electromagnetic relay that uses the magnetic field generated by the coil to move the contacts. Here's the working principle:

  1. Coil and Core: The relay has a coil of wire wrapped around a magnetic core, which is typically made of ferromagnetic material such as iron or ferrite.
  2. Magnetic Field: When an electric current flows through the coil, it generates a magnetic field around the core.
  3. Core Saturation: As the magnetic field increases, the core becomes saturated, meaning it becomes magnetically "saturated" and cannot be magnetized further.
  4. Contact Movement: The magnetic field induces a force on the contacts, causing them to move towards each other or away from each other, depending on the direction of the current flow.
  5. Contact Closure: When the contacts move, they make or break an electrical circuit, allowing or blocking the flow of current.

Types of Magnetic Relays:

  1. Normally Open (NO) Relay: The contacts are open when the coil is de-energized and close when the coil is energized.
  2. Normally Closed (NC) Relay: The contacts are closed when the coil is de-energized and open when the coil is energized.
  3. Changeover (CO) Relay: The contacts can be either normally open or normally closed, depending on the direction of the current flow.

Circuit Breaker:

A circuit breaker is an electrical device that is designed to interrupt an electrical circuit in the event of an overload or short circuit. It is a type of switch that can be reset after the fault has been cleared. Here's the working principle:

  1. Arc Chute: The circuit breaker has an arc chute, which is a chamber that contains the arc that forms when the contacts part.
  2. Tripping Mechanism: The circuit breaker has a tripping mechanism that is triggered by an overload or short circuit.
  3. Contact Separation: When the tripping mechanism is triggered, the contacts separate, interrupting the electrical circuit.
  4. Arc Suppression: The arc chute helps to suppress the arc that forms when the contacts part, preventing it from reigniting and causing further damage.
  5. Reset: After the fault has been cleared, the circuit breaker can be reset by closing the contacts.

Types of Circuit Breakers:

  1. Molded Case Circuit Breaker (MCCB): A type of circuit breaker that is designed for use in industrial and commercial applications.
  2. Air Circuit Breaker (ACB): A type of circuit breaker that uses air as the arc suppression medium.
  3. Vacuum Circuit Breaker (VCB): A type of circuit breaker that uses a vacuum as the arc suppression medium.
  4. Sulfur Hexafluoride (SF6) Circuit Breaker: A type of circuit breaker that uses SF6 gas as the arc suppression medium.

In summary, a magnetic relay uses a magnetic coil to operate a set of contacts, while a circuit breaker is designed to interrupt an electrical circuit in the event of an overload or short circuit. Both devices play important roles in electrical systems, and their working principles are based on the principles of electromagnetism.