Factors affecting the performance of the circuit breaker

There are many factors affecting the performance of circuit breaker products, which can be roughly divided into factors such as the influence of the current-carrying capacity of the circuit breaker, the impact on the protection performance of the circuit breaker, and the short-circuit characteristics of the circuit breaker.

1. Current carrying capacity of the circuit breaker

Under normal circumstances, the current carrying capacity refers to the maximum operating current allowed by the circuit breaker, that is, the rated current of the circuit breaker. However, in some special circumstances, if the ambient temperature is too high, it is necessary to lower the rated working current, that is, reduce the current carrying capacity, so that the circuit breaker can work normally at this temperature. The adjusted specific current value is in the circuit breaker product design. And application needs to be considered. For complete sets of equipment, the rated current specified in the complete set of equipment is the maximum operating current of the main switch breaker, and the rated current of the circuit breaker is not necessarily equal. The most direct reflection of the general current carrying capacity is the temperature rise of the circuit breaker terminal block. The national standard has strict regulations on temperature rise. For complete sets of equipment, the maximum temperature rise limit cannot exceed 70K, so the current carrying capacity affects the performance of the complete equipment. If the current carrying capacity is too low, the utilization rate of the circuit breaker in the complete equipment is too low, and the economic efficiency is not good; if the current carrying capacity is too high, the heating temperature rise of the device is too high, and the insulation of the complete product is destroyed. Therefore, determining the factors affecting the current carrying capacity is of great significance to the design and application of circuit breaker products in complete sets of equipment.

2. Circuit breaker protection performance

The protection performance of the circuit breaker is mainly divided into overload long delay protection, short circuit delay protection, short circuit momentary protection, under voltage protection and single phase ground protection (ground leakage current). As an important component in the complete set of equipment, the circuit breaker functions as an on-off circuit and is a device that protects the circuit. Therefore, the protection performance of the circuit breaker is also a very important performance indicator of the circuit breaker. Among them, the circuit breaker overload long-delay protection mainly refers to the ability of the circuit to open the circuit when it exceeds a certain limit of the rated current of the circuit breaker. The specified limits are all determined according to the rated current of the circuit breaker. When the circuit breaker is applied in a complete set of equipment, the current carrying capacity will usually decrease. Therefore, the design of the complete set of equipment must be considered in relation to the overload protection performance setting value of the circuit breaker and the actual current carrying capacity. Otherwise, it is easy to be in the case of loop overload. Timely tripping, causing a safety accident and causing unnecessary economic or property damage.

3. Short circuit characteristics of circuit breaker

The short-circuit characteristics of low-voltage circuit breakers are important performance and safety indicators for circuit breakers. When the circuit is short-circuited, whether the circuit breaker can open the circuit in time is an important guarantee for the safety of the electrician. Therefore, when designing and applying the circuit breaker in the complete set of equipment, it is necessary to consider the short-circuit characteristics of the circuit breaker in combination with the actual consideration. Safe operation provides protection against unnecessary property damage. The short-circuit characteristics affecting the circuit breaker are various. If the installation method is different, the circuit breaker specified in GB 14048 is generally vertically installed, but under some special conditions, it is limited by the space limitation, the ease of pulling and closing, etc. Horizontal installation is required, so the short-circuit characteristics of the circuit breaker in this case may not be fully guaranteed. At high altitudes, it is also easy to affect the short-circuit characteristics of the circuit breaker. Due to the thin air in the plateau, the arc-extinguishing performance of the air-extinguishing arc will be affected, and the arc-breaking time of the circuit breaker will be prolonged, and the contact burns seriously. The on-off capability is reduced. At the same time, the size of the space will also affect the short-circuit characteristics. In the complete set of equipment, when the circuit breaker is disconnected, there is a large energy release, which will damage the structure of the cabinet and cause damage to the equipment. Therefore, when it is necessary to carry out product design under special working conditions, it is necessary to understand the degree of influence on the short-circuit characteristics of the circuit breaker. If necessary, it is necessary to test the short-circuit characteristics of the circuit breaker under special working conditions to ensure the normal use of the equipment and avoid safety accidents. .

The above three aspects are the main considerations for the design and application of circuit breakers in complete sets of equipment.