Variable frequency drive(VFD)

VFD (Variable Frequency Drive) Panels

See Examples

This is essentially a motor starter panel with motor starting option is by variable frequency drive. VFD is a solid-state device which takes AC / DC power as power input and delivers a voltage and frequency-controlled output to the driven motor. The output could be a frequency modulated output or a Pulse width modulated (PWM) output. The modulation is controlled by a computer programmed to deliver the output according to the application. The controlled power delivery happens by controlling the firing angle on power switching semiconductors such as thyristors.

Following are the advantages of variable frequency drive panels that ordinary motor starters can’t offer

  • Power saving, accurate speed / torque control, reduction of starting current and best power factor management.

  • Regenerative breaking feature which uses the angular momentum force of the driven load converted into power and safely breaking the load to stop accurately.

Modern industrial applications need fine control of speed/ torque of the driven motor equipment such as pumps, compressors, fans, rod mills, packaging systems etc.

The VFDs produce little bit of more heat than traditional motor starters and the panel must be designed with proper thermal management.

The motor shall be energy efficient motors with very good magnetic core stamping quality which otherwise would result in lot of heat due to eddy current losses and acoustic noise.

Unwanted harmonics causes lot of performance issues. These harmonics are addressed by using proper line side or load side filter chokes.

The VFD panel will be engineered and built with all the necessary gears for safety, isolation, protection, busbars or sized & insulated conductors, push buttons, selectors switches, speed adjustment potentiometers, panel mount external display pad, control wiring from an internal control equipment or a remote control equipment, harmonic filters, wiring terminations, mounting structure/ accessories, and may be pre-programmed for target application so that it may in an almost ready to install and use.