gofer articles

A variable frequency drive is really a speed control system utilized for regulating the speed of an alternating current electric motor. The speed regulation is effected by varying the frequency of the electrical power supplied to the motor. Variable frequency drives locate wide application in ventilation systems for huge buildings, conveyors, pumps, elevator, machine tool drives, et cetera.

An alternating existing induction motor draws as much as 6 occasions its rated present in the time of commence up. The existing continues to stay high till the motor approaches the full speed. When a variable frequency drive is used to start the induction motor, a low frequency as well as a low voltage are applied to the motor. Typically, the start-up frequency is two Hz or less. When the frequency is low, the existing flow at the time of beginning will also be low. As soon as the motor is began utilizing the variable frequency drive, the applied voltage and frequency are increased at a controlled rate to ensure that the motor doesn’t draw excessive current. This technique of beginning enables the motor to as considerably as 150% of its rated torque at much less than 50% of its rated present consumption.

The variable frequency drive program consists of an AC motor, a controller and an operator interface. A controller is actually a solid state electronic power conversion device. AC input power is converted to DC intermediate energy employing a three-phase bridge rectifier technique. The DC energy is then converted to quasi-sinusoidal AC energy utilizing an inverter switching circuit.

The advantages of a variable frequency drive are the following:

~ Saving in electrical energy consumption is by far probably the most essential benefit of utilizing variable frequency drives. For example, AC motors used in ventilation systems aren’t necessary to often run at peak load. Variable frequency drives save power by controlling the volume of air necessary for a specific technique demand.

~An induction motor utilizing a variable frequency drive will last longer. The upkeep costs will also be lower. While classic starters start the motors abruptly, variable frequency drives gradually boost the speed to operating speed. This contributes to a reduction mechanical and electrical tension on the motor.

~A variable frequency drive enables greater approach control. This really is since variable frequency drives can be programmed to run the motor at the needed load, quit as per requirement and apply a specified quantity of torque.

You’ll find 3 types of variable frequency drives. These are constant voltage, continuous current and cycloconverters. One of the most crucial section of a variable frequency drive could be the inverter circuit. These units assist boost energy factor and minimize harmonic distortion.