Basic knowledge of c cabinet breaker operating mechanism

Function introduction:

In the power system, the C Cabinet Circuit Breaker Operating Mechanism plays a key role in the control and protection system. The circuit breaker can not only put certain electrical equipment into or out of the system according to the needs of the system; furthermore, when the system fails, the circuit breaker can be protected by a relay to remove the faulty equipment from the system. In order for the circuit breaker to smoothly cut off and connect the normal working current, overload and short circuit current, the circuit breaker must be able to reliably extinguish the arc during the dividing and closing process, and be able to cooperate with the reclosing gate to achieve the reclosing function.

Circuit breaker structure

• The structural form of C Cabinet Breaker Circuit Breaker Operating Mechanism is divided into insulated pillar type, tank type, and fully enclosed combination type according to the different methods of insulation to the ground. The structure of a high voltage circuit breaker is generally composed of the following five parts:
• Disconnect element：The switching element is the core element of the circuit breaker. The closing and disconnecting circuits are executed by it. It includes contacts, conductive parts, and arc extinguishing devices. The function of the arc extinguishing chamber is to extinguish the electric arc. The arc extinguishing methods include vertical blowing, horizontal blowing and vertical and horizontal blowing.
• Support elements：The support element usually refers to the porcelain column, porcelain sleeve, and other solid insulators of the circuit breaker. It is used to support the switching element and act as an insulator.
• Transmission elements：The transmission element transmits operating instructions and operating power to the switching element. It is usually composed of connecting rods, gears, crutches, hydraulic or air pipes, etc.
• Pedestal：The base is the foundation of the entire circuit breaker and is used to support and secure the circuit breaker.
• Operating mechanism：The task of the operating mechanism is to close and split the circuit breaker and maintain the closing state. Common circuit breaker operating mechanisms include electromagnetic actuators, hydraulic actuators, spring energy storage actuators, manual actuators, and pneumatic actuators. Electromagnetic, pneumatic, hydraulic and other operating mechanisms should also be required to work reliably when the closing voltage, power supply, air pressure, or hydraulic pressure changes within a certain range.

• Also, when the circuit breaker closes a circuit with a short circuit fault, the circuit breaker will automatically shut off. If the closing order is not lifted in time, the circuit breaker will close again after splitting, and then again. We call the phenomenon of a circuit breaker splitting a short-circuit fault circuit several times in a row as “jumping”. When a “jump” occurs, the circuit breaker will split the short circuit current several times in a row, causing serious burns to the contacts and even causing the circuit breaker to explode. Generally, there are two ways to prevent circuit breakers from “jumping”: mechanical and electrical.
• Basic technical parameters of circuit breakers
• Rated voltage：The voltage at which the circuit breaker is operating normally.
• Rated current：The current a circuit breaker can pass through over a long period of time.
• Rated switching current：The maximum short circuit current that a circuit breaker can switch off at rated voltage without preventing it from continuing to operate. This parameter indicates the breaking ability of the circuit breaker.
• Dynamic stable current：The maximum peak current the circuit breaker can withstand in the closed position. This parameter indicates the ability of the circuit breaker to withstand the electric force effect of a short circuit current during a short circuit.
• Thermal stabilization current：The effective value of the current that the C Cabinet Breaker Circuit Operating Mechanism can withstand within a specified period of time. This parameter indicates the ability of the circuit breaker to withstand the thermal effects of the circuit breaker’s current.
• Shifting time：Splitting time is a parameter that indicates how fast the circuit breaker breaks off. Includes intrinsic break time and burn time. Intrinsic breaking time refers to the time interval between the circuit breaker receiving a splitting command and the contact separation; combustion time refers to the time interval between contact separation and complete combustion of each phase. The sum of the inherent break time and burn time is called full break time. The shorter the full shutdown time, the faster the circuit breaker splits.
• Closing time：Closing time refers to the time interval between C Cabinet Circuit Breaker Operating Mechanism receiving a closing command until all phase contacts are in contact.
• Synchronization time between minutes and closing phases (synchronous)：Synchronicity refers to the time interval between the first phase of the action to be completed and the phase where the last action is completed when dividing and closing. The time is required within a few ms. Unbalanced current will be generated during various periods of time when they are out of sync, which may have a certain impact on protection.
• No current interval time：The no-current interval refers to the period of time (300 ms) during the automatic reclosing process of the circuit breaker, the circuit breaker trips, and the arc of each phase extinguishes until the circuit breaker coalesces the contact and pre-breaks down.
• Metal short connection time：Metal short connection time refers to the period of time (40 to 75 ms) during the automatic reclosing process, when all of the circuit breaker’s reclosing contacts are connected until the circuit breaker trips again, and the contacts have just stopped.
• Rated power supply voltage for closing coils and splitting coils：AC voltage is 220V, 380V; DC voltage is 48V, 110V, 220V. The closing coil is generally equipped with one set, and the split gate coil must be reliable. Generally, it can be equipped with two or more sets.

Auxiliary contacts for circuit breakers

C Cabinet Breaker Operating Mechanism relies on the changing opening and closing positions of its own normally open and normally closed contacts to connect the circuit breaker mechanism, trip control circuit and audio signal circuit to achieve the purpose of the circuit breaker disconnecting or closing the circuit, and can normally emit an audio signal, start the automatic device, and protect the locking circuit, etc. When the auxiliary contact of the circuit breaker is used to join or jump the circuit, there should be a delay in order to achieve reliable closing of the circuit breaker.