What is VFD variable frequency drive?

Question

some of the manufacturers name and availability in india,chennai dealer name

How VFDs used for energy saving purpose

Answer 1

The speed of an AC induction motor is given by the formula Speed = 120 f / P where f is the frequency and p is the number of poles.

Since we cannot change the poles of a motor, the best option is to vary the frequency.

Variable Frequency Drives consists of two stages, a converter and an inverter. The converter converts the incomming AC into DC. The inverter again converts the DC into AC at the desired frequency and voltage (V/F).

There are two types of variable frequency drives - Normal VFD and Sensorless Vector Drives.

Normal VFD's have a linear programmable Frequency and Voltage characteristic, irrespective of the load torque and speed requirement.

Sensorless VFD's take into account of the dynamic characteristics of the motor like speed, torque, acceleration and adjust the output voltage and frequency of the drive.

Since the drive runs at the required controlled speed at a decreased frequency and voltage and not at the full ratings, the current consumption also decreases. Hence they save energy.

Also they have many facilities like soft start which prevents shock loading of machinery and extends the life of machinery. They also protect motors from burn out by sensing the motor current and shutting down in case of overload (electrical or mechanical).

If u require more details like dealer address etc., u can send me a message.

Answer 2

A Variable Frequency Drive (sometimes abbreviated VFD) is system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. A variable frequency drive is a specific type of  adjustable speed drive. Variable frequency drives are also known as adjustable frequency drives (AFD), variable speed drives (VSD), AC drives or inverter drives.

Answer 3

As stated in the previous answer, a VFD is for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor.

For example, in a chilled water air conditioning system some areas may need AC but many areas may not need it, at a particular time. When a common pump is used to circulate chilled water to all the areas, more water will be circulated than what is required for the AC load at that time.

By introducing a VFD drive coupled with proper sensors to sense the reduction in load, the speed of the pump can be reduced so that qty of water circulated is as close as possible to the cooling demand. Thus the pump consumes less energy or current, than its full load current.

Wherever there is a possibility of the load of the driven motor  varries with time, VFDs offer the best choice to reduce the energy consumption.