How to select circuit breaker

Circuit breaker is an important protective equipment for connecting and disconnecting circuits in power system, which is widely used in industry, construction, transportation and other fields. Reasonable selection of circuit breaker is not only related to the safe operation of the circuit, but also directly affects the service life and maintenance cost of the equipment. This paper will introduce the selection method of circuit breaker from the aspects of basic parameters, use environment, load characteristics and protection function.

First, clear the rated current and voltage

When selecting a circuit breaker, it is first necessary to determine whether its rated current and rated voltage meet the circuit requirements. Generally, the rated current of the circuit breaker should be slightly larger than the maximum working current that may occur in the circuit to prevent misoperation. The rated voltage should be equal to or higher than the working voltage of the line to ensure the stable operation of the equipment within the normal voltage fluctuation range.

Second, consider the use environment

The use environment of circuit breaker has an important influence on its performance. For example, in high temperature, humid, dusty or corrosive gas environment, products with corresponding protection levels should be selected. For outdoor circuit breakers, it is necessary to have good rain, dust and ultraviolet resistance. In addition, high altitude will affect the insulation performance of the circuit breaker, so it is necessary to choose a model suitable for high altitude conditions.

Third, select the type according to the load characteristics

Different types of loads have different requirements for circuit breakers. The current of resistive load (such as electric heater) is stable, and standard circuit breaker can be selected; However, the starting current of inductive load (such as motor) is large, so D-type circuit breaker with high instantaneous tripping ability should be selected. At the same time, for the equipment that starts and stops frequently, the mechanical life and electrical life of the circuit breaker should also be considered.

Fourth, pay attention to the protection function configuration

Modern circuit breakers usually have many functions, such as overload protection, short-circuit protection, under-voltage protection and so on. In the process of type selection, the appropriate combination of protection functions should be selected according to different application scenarios. For example, in data centers and other places that require high continuity of power supply, intelligent circuit breakers with remote monitoring and automatic reset functions should be selected.

Five, consider the installation mode and compatibility

The installation methods of circuit breakers mainly include fixed type, plug-in type and drawer type. In practical application, it should be selected according to the structure and maintenance convenience of the distribution cabinet. In addition, the cooperation between the circuit breaker and the upper and lower protection devices is also very important, and it is necessary to realize selective protection through reasonable differential cooperation to avoid large-scale power failure when it fails.

Six, brand and after-sales service

Choosing well-known brand circuit breakers can not only ensure the product quality, but also get good technical support and after-sales service. It is recommended to know the technical strength of the manufacturer, product certification and user reputation before purchasing to ensure the safety and reliability of the selected products.

In a word, the selection of circuit breaker is a systematic project, which needs to consider many factors comprehensively. Only on the basis of fully understanding the circuit parameters and use requirements, can we select the circuit breaker with superior performance and reasonable economy, and provide guarantee for the safe and stable operation of the power system.