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Frequency converter (hereinafter referred to as VFD) as a high-tech electronic and electrical products using frequency conversion and microelectronics technology, so there is a certain demand in the use of environmental requirements. If a VFD wants to use efficiently and safely, the following problems must be considered, otherwise it may lead to serious problems in operation efficiency and safety.

1、 Physical environment

1. Ambient temperature:

When the temperature and temperature difference of the application site is large, it will lead to condensation inside the VFD, which will lead to a great reduction in the internal insulation performance, and even a probability of short circuit. Therefore, if necessary, we need to add desiccant and heating device in the box.

2. Corrosive gas:

If there is a high concentration of corrosive gas in the use environment, it will continue to corrode the leads of components, printed circuit boards, etc. at the same time, it will also accelerate the aging of plastic devices, resulting in the decline of insulation performance. In this case, we should make the control box into a relatively closed structure, and ventilate through specially designed vents.

3. Vibration and shock:

When the control cabinet with VFD is subject to mechanical vibration and impact, it will cause poor electrical contact. At this time, in addition to improving the mechanical strength of the control cabinet and keeping away from the vibration source and shock source, the anti-seismic rubber pad should also be used to fix the vibration components such as the electromagnetic switch outside and inside the control cabinet. After a period of operation, the equipment shall be inspected and maintained.

4. Operating temperature:

VFD is a high-power electronic component, which is easily affected by the working temperature. The product is generally required to be 0 ~ 55 ℃. However, in order to ensure the safety and reliability of the work, it should be considered to leave room for use, and the temperature should be controlled below 40 ℃. In the control box, VFD should be installed on the upper part of the box, and the installation requirements in the product manual should be strictly observed. It is not allowed to install the heating element or easy heating element close to the bottom of VFD.

2、 Electrical environment

1. Prevent electromagnetic interference:

Due to the rectification and frequency conversion in the work of VFD, a lot of interference electromagnetic waves are produced around the VFD. These high-frequency electromagnetic waves have certain interference to the nearby instruments. Therefore, the instrument and electronic system in the cabinet should use metal shell to shield the interference of VFD to the instrument. All components shall be reliably grounded. In addition, shielded control cables shall be selected for the wiring among electrical components, instruments and meters, and the shielding layer shall be grounded. If the electromagnetic interference is not handled properly, the whole system will be unable to work, resulting in the control unit failure or damage.

2. To prevent over-voltage at input terminal:

The input end of VFD power supply often has overvoltage protection, but if the high voltage at the input end works for a long time, the VFD input end will be damaged. Therefore, in practical application, it is necessary to verify the input voltage of VFD, single-phase or three-phase and the rated voltage of VFD. Especially when the power supply voltage is extremely unstable, there should be voltage stabilizing equipment, otherwise it will cause serious consequences

3、 Grounding

If you want to ensure the sensitivity of the control system, noise suppression ability, the most critical is the correct grounding for VFD. The smaller the grounding resistance of VFD grounding terminal e (g), the better. The cross-sectional area of grounding wire should be ≥ 2mm2, and the length should not exceed 20m. The shielding layer of the signal input line should be connected to e (g), and its other end must not be connected to the ground terminal, otherwise it will cause signal fluctuation and make the system oscillation. The VFD and the control cabinet should be electrically connected. If the actual installation is difficult, the copper core wire can be used for bridging. The grounding of power equipment and VFD should not be in the same place, and should not be grounded together.