Normal selection and matching of inverter - Xinjie

We want to make sure that the capacity of the inverter is matched. First of all, according to the nature of the load, the correct type of inverter is selected. The general criterion is what is the nature of the load characteristics with what characteristics of the inverter, the following is mainly for pumps and other equipment to clarify.

Normal selection and matching of inverter - Xinjie

Normal selection and matching of inverter - Xinjie

When selecting the inverter, the current value of the actual motor should be used as the basis for the selection of the inverter, and the rated power of the motor can only be used as a reference. Secondly, it should be fully considered that the output of the inverter contains higher harmonics, which will form the power factor and efficiency of the motor.

Voltage matching: The rated voltage of the inverter is consistent with the rated voltage of the motor.

Current matching: For ordinary centrifugal pumps, the rated current of the inverter is consistent with the rated current of the motor. For special loads such as deep-water pumps, it is necessary to refer to the motor performance parameters to determine the inverter current and overload capacity with the maximum current. The current setting of the inverter should not be less than 1.1 times of the rated current of the motor, and the maximum current is generally set to 1.5 times of the rated current of the motor.

About one-to-many

One tow is one inverter with multiple motors. The capacity of the inverter is the sum of the capacity of multiple motors (based on the current), and it is best to expand it by another 10%-15%. At the same time, it is necessary to ensure that each motor is properly loaded, how much strength is produced, neither empty running, nor overloading, each performing its own duties, cooperating with each other, and coexisting peacefully; But the control is not good, some of the load is heavy, some of the load is light, some are tired, some are idle, and as a result, the motor with the heavy load is heated and burned, and the whole system is paralyzed, and the big loss is due to the small loss. Therefore, when it drags on for a long time, you must be careful.

So, on the other hand, drag one more, multiple inverters with one motor, the answer: definitely forbidden!!

About cables

If the inverter wants to run with a long cable, it is necessary to take measures to suppress the influence of the long cable on the ground coupling capacitance at this moment to avoid the lack of output of the inverter, so in this case, the capacity of the inverter should be expanded by one gear or the output reactor should be installed at the output end of the inverter. When the inverter is used to operate several motors connected in parallel, it must be considered that the sum of the length of the inverter-to-motor cables is within the allowable range of the inverter.

For special applications

1. If the ambient temperature is high, the switching frequency is high, the altitude is high, etc., which will cause the capacity reduction of the inverter at this moment, and the inverter needs to be expanded by one gear.

2. When the inverter is used to drive the high-speed motor, because the reactance of the high-speed motor is small, the output current value increases due to the increase of high-order harmonics. Therefore, the capacity of the inverter used for high-speed motor is slightly larger than that of ordinary motor.

3. When driving the explosion-proof motor, the inverter does not have an explosion-proof structure, and the inverter should be set outside the dangerous place.

4. When selecting the inverter, it is necessary to pay attention to whether its protection level matches the situation on site.

other

1. When the inverter drives the wound rotor asynchronous motor, most of the existing motors are used. It is easy to overcurrent tripping caused by ripple current, so it is necessary to choose an inverter with a slightly larger capacity than the general capacity.

2. In the case of loads with large torque fluctuations such as compressors and vibrating machines and peak loads such as hydraulic pumps, it is necessary to understand the power frequency operation and select the inverter with a rated output current greater than its maximum current.

3. When the inverter controls the roots blower, because its starting current is very large, it is necessary to pay attention to whether the capacity of the inverter is large enough when selecting the inverter.

4. When the inverter is used to drive the gear reducer motor, the application range is restricted by the lubrication method of the gear rolling part. Do not exceed the maximum speed tolerance.

5. Single-phase motors are not suitable for inverter drive.

The influence of the interval between the inverter and the motor on the system and the method

In industrial application sites, the spacing between the inverter and the motor installation can be roughly divided into three situations: source and far spacing, middle spacing and near spacing. Within 20m is the near interval, 20-100m is the middle interval, and more than 100m is the far interval.

If the inverter and the motor are close to each other within 20m, they can be directly connected to the inverter;

Regarding the intermediate interval between the inverter and the motor from 20m to 100m, the carrier frequency of the inverter needs to be adjusted to reduce harmonics and interference; For the long-distance connection between the inverter and the motor of more than 100m, it is necessary not only to moderately reduce the carrier frequency, but also to install an output AC reactor.

Normal selection and matching of inverter - Xinjie

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