How many amperes of miniature circuit breakers should be used for a three-phase 4KW motorChoose small circuit breakers for electric motorsIs skill important? We can now exchange this practical experience with the engineers at Weikewei. Because if choosingIf the ampere parameter of the circuit breaker is purchased too large, how many times the actual ampere current of the motor? Can this still provide protection? When choosing a circuit breaker (air switch) for household use, only consider the load current. As long as the rated working current of the circuit breaker is greater than the maximum load current under normal conditions in your home, leave a little margin. You can add up the power of appliances that may be used simultaneously at home, such as 3 air conditioners with 3000W, electric water heaters with 1000W, lighting with 500W, microwave ovens with 800W, washing machines with 300W, and others with 1000W. Adding up 6600W, the current is approximately 6600/(220X0.85)=35A. This way, you can choose a 40A air switch.

The problem is about 5000W, so the current is approximately 27A. Using a 32A circuit breaker is sufficient. Of course, enlarging the first size with 40A is also acceptable. But don't make it too big, otherwise the electrical malfunction will overload and the circuit won't trip during the idle meeting. Small circuit breakers cannot be used alone for motor protection, although D-type products have instantaneous characteristics of 10-20 inches, they will not cause misoperation when the motor starts. However, the overload characteristics of circuit breakers cannot protect against motor overload current (referring to low overload current, not short-circuit current). The stator winding of the electric motor can only withstand an overload current of less than 20%, while the overload setting value of the circuit breaker is 145% In. The insulation of the stator winding has burned out, but the circuit breaker still doesn't operate. If you insist on using a circuit breaker, you can choose to use a circuit breaker for motor protection or a small circuit breaker in conjunction with a thermal relay. Choosing a 16A circuit breaker, may I ask what circuit this motor is used for, such as fans, water pumps, etc. There are differences in the selection of motors for different purposes. The motor is mainly overloaded, and when it reaches a certain heat level, the circuit breaker will automatically cut off the power supply. A 40A one is sufficient. Plastic shell circuit breakers are mainly used in AC/DC networks for distribution or protection of motor overload, short circuit, undervoltage, and overvoltage. Used for infrequent connection and disconnection of lines under normal operating conditions. Special requirements can be achieved through shunt and alarm contacts. The short-circuit cutting ability can reach up to 100ka. But maintenance is slightly more complicated. Small circuit breakers are mainly used for household purposes, with only short circuit and overload protection. However, they are small in size, low in price, and easy to maintain, and are generally used at home. The maximum cutting capacity shall not exceed 10ka High section circuit breakers are basically the same as small circuit breakers. But in smaller volumes, lower prices can achieve higher cutting capabilities.

When choosing a circuit breakerThere are many aspects and matters that need to be considered, and it is impossible and unnecessary to meet all requirements in practice. Designers should have an overall understanding of the systemCircuit breakerStarting from the purpose and requirements of use, comprehensively analyze the priorities, weigh the pros and cons, grasp the important aspects, highlight important issues and give priority consideration. On this basis, a clear choice can be made断路器Specific issues of type: size of measuring range and overload capacity; Object or location being tested断路器The requirements for weight and volume are both important. If you still cannot meet your needs, then communicate with the electrical engineers at Wekeway.