Know the KW number of the motor, how big a switch you need to use, a wire, a contactor and a circuit

Knowing the number of kW, then the number of currents is about 2 times the number of kW (it is best to look at the nameplate of the motor), and select wires, contactors and circuit breakers according to the current.

If you start with a 380V motor, the power x2 is about the current, and the rest will be easy to do.

The rated current of 55kw electric buried Tongliang machine is 110, 200 for the wide circuit breaker, and 160 for the contactor.

It is better not to start the 55kw motor directly:

The direct start of the KW motor will produce a large impulse current, which will have a great impact on the power grid. Damage to nearby power grids.

The direct start of the KW motor has a large starting current, and the contacts of the contactor are easy to burn.

3. Generally, motors below 15kw are considered to start directly.

A contactor should be OK. It is recommended that you switch to the wheel collision star triangle startup method, which is more safe and reliable.

Circuit breaker refers to a switchgear that can close, carry and break the current under normal circuit conditions, and can close, carry and break the current under abnormal circuit conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use, and the division of high and low voltage boundaries is relatively blurred, and generally more than 3kV is called high-voltage electrical appliances.

The 55kw motor is directly started with multiple circuit breakers and contactors.

Dear, glad to answer for you. 55kw motor direct start with how big circuit breaker and contactor Answer: 55kw motor rated current 110, circuit breaker with 200, contactor with 160.

The working current of the 55kw motor is about 60A, and the starting is used to start with a wide envy and jujube soft start or star triangle start, which can be opened with an air of 80-100A. For example, if it is used to control the forward and reverse operation of the 30kw motor, it is recommended that you use CJ20-100, and only CJ20-63 is required for extraordinary actions.

The motor is 15kw with 4 square copper cable and 50A switch.

According to the power formula p=have:i=p (

27A (calculated according to the three-phase mains, the power factor is taken.)

Check the cable ampacity meter above, choose a square copper wire is reluctant, and it is best to choose a 4 square cable. If the distance is far, 6 square copper wire can be selected. The specification of three-phase air opening is (RMM1-100S h):

Therefore, 50A air opening is optional.

The 380V motor is about one kilowatt for two amps, and your 15 kilowatt motor is rated at about 30A, and it can be 6 square meters for short-term operation, and 10 square meters for long-term operation. Simply point to one square two amps, probably so, but for small wire diameter cables, you can enlarge it, 1 square can go to 5 7A for a short time.

15 kilowatts is only about 30 currents, and it can be switched at 60A or 100A.

With 4 square copper core wires can be used for a 32 amp switch.

First of all, it is necessary to know the voltage of the electrical appliance, because the voltage is different, the current is also different, so the switch, wire, etc. selected are also different.

If you know the conversion formula (rough conversion algorithm) for the current in different voltages in a kilowatt, 220 is 4 amps. 380 is Ann and 660 is Ann. Let's say a kilowatt of current is ampere at 380 volts.

Knowing the above, convert the current of the electrical appliance, and then convert the cable. The formula is also vague, but it is very practical and works well in general. The cable has a load of 1 square millimeter and 3 6 amperes.

Why is the range so large, this is the problem of heat dissipation. For example, the load of small electrical appliances is small, and the selected cable is also small, and the heat dissipation is good, so you can take a small value. Otherwise, the larger value is taken.

From the above, you can understand that if the current of your electrical appliances is ampere in 380 volts, then the cable takes 1 to meet the load requirements.

When selecting the switch, pay attention to the electrical appliances that are several phases of electricity. If it is 220 volts, you can choose to open it single, or double open it in parallel. If it is three-phase, choose a three-phase switch. Choose the size of about 10 amps.

The 1KW motor can be directly started with 16A air, and the wire can be selected as 1 square.

10-16A can be opened empty, CJX1-16 22 contactor, square wire. The selected element is selected according to the rated current of the load, and the selected element is generally larger than the rated current of the load.