Variable Frequency Drive Installation and Notes


1) Ambient temperature

Variable frequency drive just like other electronic devices, has certain requirements about the temperature around it, generally its -10 to +40 °C. As the AC variable frequency drive internal high-power electronic parts are easily influenced by the working temperature, in order to ensure the safety and reliability of the variable speed drive, it should be considering leaving some spare room, for the best control it under 40 °C; Derating it for 40 to 50 °C, and if the temperature increase by 1 °C, the rated output current must be reduced by 1%.
If the ambient temperature is too high and changes a lot, the insulation performance of the variable frequency AC drive will greatly reduce and impact the variable frequency inverter service life.

2) Ambient humidity

Variable frequency drive and other electrical equipment have environmental humidity requirements, the ambient air relative humidity = 95% (No condensation), according to the scene work environment it may necessary to put desiccant and heater in the frequency counters boxes.

3) Vibration and shock

During the variable frequency inverter running process, we need to pay attention to avoid vibration and shock. As we all know, the variable frequency AC inverter is made up of many components assembled by welding, screw connection etc, when the variable frequency drive or ac drive control cabinet subjected to mechanical vibration or shock, will lead to the solder joints, screws and other connecting devices or connector loose or fall down, and then cause poor electrical contact, short circuit faults even worse. Therefore, in addition to improve the mechanical strength of the control cabinet, keep away from the vibration source and shock source during the variable frequency drive operation, we should install rubber gasket outside the control cabinet, and install rubber pads, shock absorption buffer between the devices and the mounting plate in the variable frequency drive control cabinet.
Usually we need to inspect and maintain the control cabinet after the equipment operation a certain time.

4) Electrical environment

A. Prevent electromagnetic interference

The variable frequency AC drive main electrical components are power module and control system hardware and software circuit, If these components and software programs are impacted by a certain electromagnetic interference, it will cause hardware circuit malfunction, software program failed and then cause accident. So, in order to avoid electromagnetic interference, the variable speed drive needs to prevent electromagnetic interference according the electrical environment. For example: the input power cord, output motor lines, control lines shall be kept away from each other; The devices and signal lines which are easily affected, should be installed as far as possible from the variable frequency AC drive; The critical signal lines should be shielded cable, it is recommended to use shield cable with 360° grounded.

B. Prevent overvoltage in input terminal

The main circuit of the variable frequency drive is consisted of power electronic parts, these devices are very sensitive on the voltage, the over voltage on input terminal will cause permanent damage of the main components. For example, some factories have their own electricity generator, power grid fluctuation is relative high, so they should have precautions on the input voltage of the adjustable frequency drive.

5) Altitude

The Variable speed drive can output rated power if it’s installed below 1000m altitude. But the output power will drop if the altitude over 1000m. The variable speed AC drive output current will be reduced when the altitude is over 1000m, if the altitude is 4000m, the output current is 40% of 1000m current only.

6) Other environment

– Avoid installing the variable frequency drive in the rain or condensation area;
– Prevent the ingress of dust, bats and metal fines;
– Avoid installing the VFD drive in the oil and salt occasions;
– Keep away from radioactive and flammable materials.