1、What is a frequency converter?

The use of power semiconductor devices on and off the role of the power frequency power supply to another frequency of the power control device, can achieve the AC asynchronous motor soft start, frequency control, improve the operating accuracy, change the power factor, overcurrent/overvoltage/overload protection and other functions of the control of the power device.

2、What are the protection functions of frequency converter?

The protection function can be divided into two categories: (1) detecting the abnormal state and then automatically correct the action, such as overcurrent stall prevention, regenerative overvoltage stall prevention.

Blocking the PWM control signal of the power semiconductor device after detecting the abnormality, so that the motor stops automatically. 

Such as over-current cut-off, regenerative over-voltage cut-off, semiconductor cooling fan overheating and instantaneous power failure protection.

3、The motor over 60Hz operation should pay attention to what problems?

(1) Machinery and devices operating at this speed to be fully possible (mechanical strength, noise, vibration, etc.); 

(2) The motor into the constant power output range, its output torque to be able to maintain the work (fans, pumps, etc., the shaft output power in the speed of the cube proportional to the increase in the speed of the speed of the so a little higher speed should also pay attention to); 

(3) Resulting in the life of the bearings to be fully taken into account;

(4) For motors of medium capacity and above, especially 2-pole motors, careful discussion should be held with the manufacturer when running at 60Hz or above.

Depending on the structure of the gearhead and the lubrication method, a number of issues need to be noted. In the structure of the gear can usually be considered 70 ~ 80Hz as the maximum limit, the use of oil lubrication, continuous operation at low speeds related to gear damage.

4、Frequency converter can be used to drive single-phase motor or use single-phase power?

Basically, it cannot be used. For single-phase motor with governor switch starting type, the auxiliary winding will be burnt when the speed range is below the working point; for capacitor starting or capacitor running type, the capacitor will be induced to explode. 

The power supply of inverter is usually 3-phase, but for small capacity, there are also single-phase power supply operation of the machine.

5、How much power is consumed by the frequency converter itself?

It is related to the type of frequency converter, operation status, frequency of use, etc., but it is difficult to answer.

 However, the efficiency of the frequency converter below 60Hz is about 94%-96%, and the loss can be estimated accordingly, but the power consumption of the inverter with built-in regenerative braking type (FR-K) will be larger if the loss during braking is also taken into consideration, and it is necessary to pay attention to the design of the operation panel.

6、What are the interference modes of inverter and how to deal with them?

Propagation mode: (1) radiation interference; (2) conduction interference.

Anti-interference measures: For the interference signal propagated through the radiation mode, mainly through the wiring and the shielding of the radioactive source and the interfered line to weaken the way. 

For the interference signal propagated through the line, mainly through the frequency converter input and output side of the addition of filters, reactors or magnetic rings and other ways to deal with. Specific methods and precautions are as follows: 

(1) Signal lines and power lines should be vertically crossed or sub-slot wiring; 

(2) Do not use wires of different metals connected to each other; 

(3) Shielding tube (layer) should be reliably grounded, and to ensure that the entire length of the continuous and reliable grounding; 

(4) Signal circuits should be twisted-pair shielded cables; 

(5) Shielding layer grounding point as far as possible away from the frequency converter, and separate from the frequency converter grounding point;

 ( 6) Magnetic ring can be used in the frequency converter input power line and output line, the specific method is: the input line in the same direction around 4 circles, while the output line in the same direction around 3 circles can be. When winding the line, it should be noted that the magnetic ring is as close as possible to the frequency converter;

(7) Generally for the interfered equipment and instruments, can take shielding and other anti-interference measures.