A medium voltage circuit breaker is an automatically operated electrical device designed to protect an electrical circuit from damage caused by overload or short circuit.Its basic function is to interrupt a high momentary current flow. Unlike a fuse,which operates once and then must be replaced,a MV circuit breaker can be reset to resume normal operation. Control and detection of the main circuit to be protected is provided by an external relay.
How Medium Voltage Circuit Breaker (MVCB) works?
A circuit breaker uses a mechanical means to separate two contacts in an arc quenching medium to interrupt the flow of electricity.
Several different type of arc quenching technologies are available-
Vacuum Interrupters
SF6 interrupters
Oil
Air magnetic
Two main type of mechanisms-
Spring
Magnetic
Components of MVCB
1.Upper contact terminal
2.Vacuum interrupter
3.Epoxy resin enclosure
4.Lower contact terminal
5.Bearing
6.Movable contact assembly
7.Contact force spring
8.Insulated push rod
9.opening spring
9.Travel adjuster
10.Transmission rod.
11.Main shaft
12.Operation assembly
13.Mechanism frame
All circuit breakers are built with two primary functions. The first is to actively control the power flowing via a specific electrical circuit. The second step is to protect equipment connected to the circuit from damage.
The MV circuit breaker, which interrupts and isolates electrical circuits, is ideal for protecting against overcurrent (or) short circuit circumstances.
The circuit breaker will have specified threshold limitations for the voltage that can pass through it.
When the present current exceeds the defined threshold, the breaker will cut power to the circuit.
This helps ensure that any equipment or other things connected to the circuit do not receive an overload of power, which could harm their internal components or possibly provide a fire danger.
These circuit breakers can operate automatically or manually. Manual MV circuit breakers will have a visible operating handle on their body. This enables a manual operator to easily activate the closure spring, interrupting the power flow to the circuit.
Manual circuit breakers are only accessible for circuits operating at voltages below 600 V.
Automatic medium voltage circuit breakers work by an electrical response. This response can be generated via a solenoid (or) an energy-storage mechanism. Regardless of how the automated response is initiated, it eventually terminates the power supply to the circuit to avoid damage from overloads & short circuits.
