Precautions for using VFD (Variable-frequency Drive)

Precautions for using VFD (Variable-frequency Drive):

1. VFD (Variable-frequency Drive) should not be installed on vibrating equipment, because the connecting screws of the main circuit in the VFD (Variable-frequency Drive) are easy to loosen, and many VFD (Variable-frequency Drive) are due to this reason. damage.

2. Wiring problem: VFD (Variable-frequency Drive) input terminal is best connected with an air starter protection current, and the value should not be too large, so as to prevent serious burning in the event of a short circuit. The "N" terminal must not be grounded. The control line should not be too long. Because this will make the control board vulnerable to electromagnetic wave interference and cause malfunction, it will also cause damage to the control board, it is best to use shielded wires longer than 2 meters. Do not install a contactor with a large current and frequent action next to the VFD (Variable-frequency Drive), because it interferes very much with the VFD (Variable-frequency Drive), and often causes the VFD (Variable-frequency Drive) to malfunction (display various Fault).

3. It is better not to rely on VFD (Variable-frequency Drive) itself to brake the VFD (Variable-frequency Drive) that often needs to stop suddenly, but to add brake resistors or use mechanical brakes, otherwise VFD (Variable-frequency Drive) is often affected The back electromotive force impact of the motor will greatly increase the failure rate.

4. If the VFD (Variable-frequency Drive) often runs at a low speed below 15HZ, the motor should be equipped with a cooling fan!

5. Dust and humidity are the deadliest killers of VFD (Variable-frequency Drive). It is best to install VFD (Variable-frequency Drive) in an air-conditioned room, or in an electric cabinet with a dust filter, and regularly clean the dust on the circuit board and radiator; VFD (Variable-frequency Drive) that has been shut down for a period of time Drive) It is best to blow the circuit board with a hair dryer before powering on.

6. When the cooling fan of some brands of VFD (Variable-frequency Drive) is broken, it will not issue overheating protection until the VFD (Variable-frequency Drive) is damaged, so when the fan makes noise, it should be replaced.

7. Some factories are powered by generators, the voltage is unstable, and the VFD (Variable-frequency Drive) is often damaged. The generators are equipped with voltage stabilizing or overvoltage protection devices, and the effect is very good.

Eight, lightning protection is also very important. Although it rarely happens, when the VFD (Variable-frequency Drive) is struck by lightning, it will be severely damaged. The VFD (Variable-frequency Drive) with constant pressure water supply is most likely to be struck by lightning because it has a lightning-inducing water pipe extending to the sky.

9. In order to prevent electromagnetic wave interference, VFD (Variable-frequency Drive) input, output, and control lines are best to use shielded wires. The wiring method of the shielding layer cannot be wrong, otherwise the effect will be reversed. If possible, use iron pipes to cover them and install filters. to lower the carrier frequency. We found that if the switching tube of the VFD (Variable-frequency Drive) switching power supply is a field effect tube (such as K series), the interference will be greater.

10. When the VFD (Variable-frequency Drive) is broken, don't give it to someone who has no maintenance experience to repair it! Otherwise, it may get worse and worse! Sometimes it is about to blow, so be sure to check whether there is a problem. Some electricians have no experience and immediately install a good fast fuse (it must not be replaced by copper wire). As a result, the VFD (Variable-frequency Drive) burns even worse. According to our experience, if the fuse is fast, most of the modules have problems, but if the module is broken, the fast fuse may not be broken. Many VFD (Variable-frequency Drive) power modules and rectifier modules are interchangeable.

11. In the process of VFD (Variable-frequency Drive) maintenance, we often encounter some VFDs (Variable-frequency Drive) that were blown up after repaired by the factory itself, and the damage is more serious than before, and it is more difficult to repair. Upon inspection, it turned out that they were using a repaired module. It is difficult to detect the repaired module with an instrument, and all parameters are completely normal, but due to the rough internal wiring, the sealing silicone grease of the transistor cannot be sealed after opening. Some such modules can be used for several months, and some can be turned on once Just blow up.

Precautions for using VFD (Variable-frequency Drive):

1. Physical environment

1) Working temperature. VFD (Variable-frequency Drive) is a high-power electronic component inside, which is easily affected by the working temperature. The product generally requires a temperature of 0-55°C. However, in order to ensure safe and reliable work, it should be considered when using it. Control below 40°C. In the control box, the VFD (Variable-frequency Drive) should generally be installed on the upper part of the box, and strictly abide by the installation requirements in the product manual. It is absolutely not allowed to place heating elements or components that are prone to heat close to the VFD (Variable-frequency Drive) installed at the bottom.

2) Ambient temperature. When the temperature is too high and the temperature changes greatly, condensation will easily appear inside the VFD (Variable-frequency Drive), which will greatly reduce its insulation performance and may even cause a short circuit accident. If necessary, a desiccant and a heater must be added to the box.

3) Corrosive gas. If the concentration of corrosive gas is high in the use environment, it will not only corrode the lead wires of components, printed circuit boards, etc., but also accelerate the aging of plastic devices and reduce the insulation performance. In this case, the control box should be made into a closed structure. , and ventilate.

4) Vibration and shock. When the control cabinet equipped with VFD (Variable-frequency Drive) is subjected to mechanical vibration and shock, it will cause poor electrical contact. At this time, in addition to improving the mechanical strength of the control cabinet and keeping it away from vibration sources and shock sources, anti-seismic rubber pads should be used to fix vibration-generating components such as the external and internal electromagnetic switches of the control cabinet. After the equipment has been in operation for a period of time, it should be inspected and maintained.

2. Electrical environment

1) Prevent electromagnetic wave interference. VFD (Variable-frequency Drive) generates a lot of interference electromagnetic waves around due to rectification and frequency conversion during work. These high-frequency electromagnetic waves have certain interference to nearby instruments and instruments. Therefore, the instruments and electronic systems in the cabinet should use metal casings to shield the VFD (Variable-frequency Drive) from interfering with the instruments. All components should be reliably grounded. In addition, the connection between electrical components, instruments and instruments should be shielded control cables, and the shielding layer should be grounded. If the electromagnetic interference is not handled well, it will often make the entire system unable to work, resulting in failure or damage to the control unit.

2) Prevent overvoltage at the input terminal. The VFD (Variable-frequency Drive) power supply input often has overvoltage protection, but if the input terminal has a high voltage for a long time, it will damage the VFD (Variable-frequency Drive) input terminal. Therefore, in actual use, it is necessary to verify the input voltage of the VFD (Variable-frequency Drive), single-phase or three-phase, and the rated voltage of the VFD (Variable-frequency Drive). Especially when the power supply voltage is extremely unstable, there must be a voltage stabilizing device, otherwise it will cause serious consequences.

3. Grounding

The correct grounding of VFD (Variable-frequency Drive) is an important means to improve the sensitivity of the control system and the ability to suppress noise.