Working of Circuit Breaker

A circuit breaker is an electrical switch that disconnects the power flow when it detects a problem. This is a safety feature that eliminates the need for fuses to replace blown ones.The mechanism of a circuit breaker includes a protective relay pilot device that senses a fault. It also includes an operating mechanism that opens or shuts the breaker to fulfill its protective function.

Used Circuit Breakers safety mechanism

Used circuit breakers protect electrical wires from damage. When you try to push more current through a system than it is designed for, the wires heat up and the insulation can degrade or even melt. Circuit breakers have a built-in safety mechanism that senses this and "trips" to stop the flow of current before the system can burn down or catch on fire.The main body of the circuit breaker contains two sets of contacts that are called the "main" or current carrying contact set and the arc quenching contact set. The tips of the contact sets are coated with a copper-tungsten material to provide arc quenching. The moving contacts are separated by a puffer cylinder that can move upward and downward.

As the arc separates, it creates a high-voltage stress across the contact gap that can cause damage to the equipment if not quickly interrupted. When the arc is quenched, the transient recovery voltage begins to decrease rapidly and the moving contact gap reaches its dielectric strength (breakdown) where it cannot re-establish an arc.When the control panel sends a opening command, a mechanical operating mechanism produces energy that is stored in a charged opening spring. As this energy is transferred to the interrupter, the spring releases and moves the drive rod connected to the cylinder in a linear direction. This causes the arc to disconnect from the contact set and the cylinder to move down. circuit breakers for sale at surplusrecord.

Molded Breakers automatically interruption

The molded circuit breaker (MCCB) is a switch that automatically interrupts the current in an overloaded electric circuit or when a short circuit occurs. It replaces the fuse and knife switch used in older electrical systems. Overloaded circuits are the most common reason for a circuit breaker to trip. They occur when everything that is using electricity on a circuit demands more than the circuit can handle, creating dangerous levels of heat. The breaker will typically "trip" when the protective relays detect this, preventing further damage.

The operating mechanism in a molded breaker creates and stores the energy needed to operate it. There are many different types of mechanisms that use varying methods to provide the energy to close and trip the breaker contacts.

A spring-operated mechanism uses a closing spring that is mechanically charged by the operating mechanism and held in its compressed position by a latch. When a close command is received, the armature of the close coil moves this latch and releases the closing spring. This pushes the main contacts closed and also causes a crank on the tripping springs to compress them.

Once the tripping springs are fully compressed, they will pull against a wheel abutment and cause the arm to rotate the trigger shaft 2 through top dead center. This forces the cam 17 against the engagement abutment on the wheel abutment and drives it against the lever 27.

Vacuum Circuit Breakers and metallic ions

Vacuum circuit breakers use a vacuum as an arc extinction medium. When they are opened, their current-carrying contacts are separated into two contact points in a permanent vacuum (10-7 to 10-5 torr). Metallic ions, electrons, and vapors produced during the arc quickly condense on the surfaces of the contacts. This results in an extremely short arc gap and rapid extinction, as well as a fast recovery of dielectric strength. This makes them an ideal interrupting device for high-speed switching applications.This mechanism also has the benefit of dealing with severe recovery transients that occur during short line faults and other types of load switching. Compared to oil and air circuit breakers, vacuum breakers have a lower current chopping level and are capable of clearing large loads without any difficulty. circuit breakers for sale at surplusrecord.

The operating mechanisms of vacuum circuit breakers are designed to allow the opening and closing springs to be charged separately. They also have separate latching and actuating devices that can be activated manually or electrically. These features help to ensure thebreaker operates as intended in normal operation and protects the circuit.When the operational mechanism of a vacuum circuit breaker fails to open properly, there may be a problem with the mechanical components or the secondary circuit. It is important to determine the cause of the issue before taking any action. If the problem is a mechanical issue, it can be addressed by examining the gaps between all of the operating mechanism's connecting parts. If any of these are not qualified, they should be replaced with new parts that have a higher hardness.

Air Circuit Breakers

Air circuit breakers are designed to interrupt current flow when a fault is detected. When the electrical contacts open to interrupt a current, there is a tendency for an arc to form between them, which can cause damage to equipment. The arc produces conductive ionized gases and molten or vaporized metal, which can cause further short circuits or fires. To prevent these hazards, circuit breakers have various features to divide and extinguish the arc.

In an air circuit breaker, the mechanism is driven toward its closed position by mechanical energy stored in closing springs. When a close command is received at the local control switch or remotely, these springs are compressed and latched by a close coil. As the mechanism nears its closed position, the 52-1/b contacts in the close coil path open, de-energizing the close coil and allowing the closing springs to discharge. Once the closing springs are discharged, a contact in the anti-pump scheme closes to disable another closing operation until an open command is received.

Once the arc is split, an opening command can be sent to the trigger control mechanism, which will initiate a trip operation by rotating an outlet member of the drive mechanism, a trigger shaft, in the direction of arrow f1. This will recock the spring 12, causing arm 11 to come into abutment with the wheel abutment cam 17, pushing the rod 6A against the wheel abutment and triggering the opening operation.