What is the standard for the contactor of the motor to choose

The current of the 55kw motor is between 110A, (calculated according to the empirical algorithm of two currents per kilowatt), choose CJ20-150 contactor, and choose according to the current of the load.

1. The principle of selection of contactors.

Select by category of use:

In practice, most of the cage motors are basically selected according to the AC-3 use category.

Determine the capacity level:

The capacity of the contactor, that is, the determination of the rated current of the main contact under the technical conditions such as rated voltage, should pay attention to the following points:

1) The influence of working system and working frequency:

When selecting a contactor, it should be noted whether the control object is a long-term working system or a repetitive short-term working system. When the operating frequency is high, it is also necessary to consider the capacity to increase the rated current of the contactor. Contactors with silver, silver alloy or silver-inlaid contacts should be used as much as possible, such as KSDZ U series products.

2) Influence of environmental conditions.

The environment of the production process is relatively harsh, with serious dust pollution, poor ventilation conditions, and high workplace temperature. It is necessary to take technical measures to reduce the capacity of the contactor for the selection of contactors.

2. Quick check of the rated current of the contactor.

For example, a Y180L-4, 22KW motor should be equipped with a U60 contactor from the cheat sheet. The motor is rated at 60A, the contactor is rated at 60A, according to the general AC-3 working category, the contactor can control 380V motor power is 30KW, and now it controls 380V

The 22kw motor is used for capacity reduction.

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When the contactor is selected according to the rated power of the motor 1, the voltage should meet the rated voltage requirements of the circuit, and the rated current should be greater than (or equal to) the current of the circuit, for example, if the circuit current is 218A, the contactor of 250A should be selected; 2. The rated current multiple refers to the ratio of the starting current of the motor to the rated current, the starting current of the general motor is 5-7 times of the rated current (effective value), and the maximum can be 12 times when converted to the peak; 3. The contactor design has been considered to be able to withstand the impact of the starting current, so the contactor selection does not need to consider the influence of the starting current, that is, there is no need to select the contactor according to the starting current, which is too much loss. Hope mine can help you <>

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The contactor is selected according to the starting current or the rated power of the motor.

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Pro, the contactor selection is based on the rated power of the virtual motor 1 When the contactor is selected, the voltage should meet the rated voltage requirements of the circuit, and the rated current should be greater than (or equal to) the current of the circuit wheel, for example, if the circuit current is 218A, the contactor of 250A should be selected; 2. The rated current multiple refers to the ratio of the starting current of the motor to the rated current, the starting current of the general motor is 5-7 times of the rated current (effective value), and the maximum can be 12 times when converted to the peak; 3. The contactor design has been considered to be able to withstand the impact of the starting current, so the contactor selection does not need to consider the influence of the starting current, that is, there is no need to select the contactor according to the starting current, which is too much loss. Hope mine can help you <>

Do you have any other questions?

For example, the electric motor, star delta start, how many amperes of contactor should be selected.

Pro, mainly depends on the line control, generally first let the star shape and then put into the electric Tan Zen noise source, and then switch to the triangle operation. In this case, the contactor for star start can be a little smaller, and it is not easy to be damaged, and 63A can be used; The power supply and triangle operation contactor should be upgraded by one level, which can be 100A; 25 square millimeters of copper core wire is used.

How to choose a motor starter contactorAccording to the rated current of the motor, it is generally a multiple of the rated current of the motor, and there will be a description of how much power the motor is suitable for on the contactor. A model larger than the instructions on the contactor will do.

If possible, choose as large as possible, for example: 4kw motor. with 18 or 25 A contactors.

Motor. with 18 or 25 A contactors.

Electric Hidden Hunger Machine. With a 32 or 25a contactor.

11kw motor. With a 32 or 40A contactor.

Motor. Grind the return toucher with a 50 or 65 A stove.

22kw motor. With 80 or 65A contactors.

37kw motor. With a 95 or 115A contactor.

The current value selection of the three-phase motor contactor should be determined according to the rated current of the motor. In general, the rated current of the contactor should be the same or slightly larger than the rated current of the motor to ensure that the contactor can work stably. When selecting a contactor, factors such as the starting current and maximum current of the motor should also be considered.

It should be noted that in addition to the current value, the quality, brand and reliability of the contactor should also be considered to ensure the stable operation of the equipment.

1. The motor selection AC contactor should be selected according to the motor power to choose the appropriate size, times, generally there is a model in the selection manual, and you must pay attention to the matching of the auxiliary contacts, do not buy back the auxiliary contacts are not enough.

2. The AC contactor is mainly composed of four parts: (1) electromagnetic system, including suction coil, moving iron core and static iron core; (2) The contact system, including three groups of main contacts and one to two groups of normally open and normally closed auxiliary contacts, which are connected with the moving iron core and linked with each other; (3) Arc extinguishing device, the AC contactor with large capacity is generally equipped with an arc extinguishing device, so as to quickly cut off the arc and avoid burning out the main contact; (4) Insulated shells and accessories, various springs, transmission mechanisms, short-circuit rings, binding posts, etc.

3. A motor is a device that converts electrical energy into mechanical energy. It uses an energized coil (that is, the stator winding) to generate a rotating magnetic field and acts on the rotor (such as a squirrel cage closed aluminum frame) to form a magnetoelectric dynamic rotational torque. The motor is divided into DC motor and AC motor according to the different power sources, and most of the motors in the power system are AC motors, which can be synchronous motors or asynchronous motors (the magnetic field speed of the stator of the motor is not synchronized with the rotation speed of the rotor).

The motor is mainly composed of a stator and a rotor, and the direction of the energized wire in the magnetic field is related to the direction of the current and the direction of the magnetic inductance line (magnetic field direction). The working principle of the motor is the effect of the magnetic field on the current force, which makes the motor rotate.

Generally, the current of the motor is calculated according to the current amount of 2A per kW (kW), for example, the rated current of the 5kW motor is 2*5=10A, and the contactor can be selected according to the rated current of the motor, as in this example, the contactor with a capacity of 10-12A is selected.

According to the rated current of the motor, it is generally 15 to 20 times the rated current of the motor, and there will be a description of how much power the motor is suitable for on the contactor. Generally, choose a larger one, so as not to give you the load indiscriminately.

To give you a formula, you just need to be more than 2 times your current.

Not less than times the rated current, the selection requirements are as follows.

1: The motor category and the contactor category need to be the same (e.g., the motor AC-3 contactor should also choose the AC-3 category).

2: The current of frequent start should be larger than that of intermittent large (not less than 2 times of the rated current, and the latter can be used lower).

3: Environmental requirements must be considered, such as: temperature, altitude, humidity are subject to the instructions of each brand.

4: Step-down start-up motor The size of the contactor is determined by the step-down performance (for example, the current of star-delta start-up is one-third of the rated current and one-third of the root number).