Control panels with VFD – Variable Frequency Drives

The variable frequency drive control panel, also known as a VFD panel or AC drive electrical control panel, consists of an internal VFD mounted inside an electrical cabinet along with external control, protection and electrical components. It is a frequency conversion device used to control three-phase AC motors (including fans and pumps) at variable speeds to save energy.

VFD panels use a closed cabinet structure and often have a protection class of IP20, IP21 or IP30, while some panels can even reach IP64, IP65 or IP66 depending on the usage environment. The major features of the electrical control panel and frequency conversion depend on the internal VFD and other component configurations. The variable speed drive is a dedicated panel component. Generally, VFD panels require custom fabrication based on the desired operating environment, such as constant flow control panels (one panel controls 1, 2 or 3 pumps, for example), escalator control panels, central panels of air conditioning circulation pump and fan control panels.

Control panels with VFD - Frequency converter for: Pump and motor control, Industrial fans and exhaust fans, conveyor belts, HVAC.

Constant flow control, air compressors, central air conditioning, port equipment, production equipment, boilers, paper and food equipment.

Large machine applications such as conveyors and compressors.

IP (Tables IP 54, IP 55, IP 65).
Powder coated CRCA steel and stainless steel from the following classes: 304, 316 and 316L.
Case brand: CSE, Rittal, Hoffman and Eldon.
Wall or floor mounting options


Standard Guidelines for VFD that we at West Automation apply

  • Voltage between ground and neutral as well as the earth loop impedance. It has to be below 0.5 V.
  • All of the wires and connectors in the VFD panel are installed and tightened correctly by double-checking each one.
  • Cable dressing, ferrule, and connection to the appropriate polarity, as well.
  • All of the wiring was completed in accordance with the electrical drawing or not.
  • We make sure the VFD is securely fastened in the panel and look for any VFD damage.
  • All of the fuses, line chokes, and harmonic filters are connected correctly in the electrical panel.
  • Verify that only the chosen model is installed by comparing the motor and VFD specifications.
  • Make sure the motor and VFD are both securely grounded.
  • Full test check list.
  • VFD isn't always utilized by itself. It serves as an interface for PLC and other control systems. Thus we check the control wiring from the PLC or, if communication is utilized, the port connection if such a method is employed.
  • As the VFD dissipates a lot of heat, make sure that the area surrounding it is properly cooled and ventilated, and check to see if the internal fan is functioning properly.
  • Check the installation of the dynamic brake resistor boxes as well as the installation of the mechanical brakes if they are utilized with the motor.

Testing and Commissioning of VFDs

Before turning on the VFD, make sure the input supply voltage is as specified.

Power on the VFD after confirming. Check the DC voltage first at the VFD's DC bus voltage output.

The fan on the VFD begins to run as soon as it is powered on. Check to see if it is appropriate.

Programming the necessary parameters into the VFD is done at this phase. The most frequently used ones include acceleration and deceleration times, motor control parameters (current, voltage, rpm, frequency, etc.), IO configuration (inputs and outputs of VFD control terminals), and control parameters (source of command and speed reference).

Test the VFD in a run instruction and a speed reference, then check to see if the motor is spinning in the desired direction.

We check that the motor is operating within its rated parameters; the VFD should not trip. The motor should not be making any unusual noises when it is running.

If the application calls for auto-tuning, then it has to adhere to the tuning instructions specified in the VFD manual.

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