Variable Frequency Controller

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40 HP ALLEN BRADLEY VARIABLE FREQUENCY CONTROLLER 1336    US $1,500.00

5 HP RELIANCE AC VS DRIVE VARIABLE FREQUENCY CONTROLLER    US $600.00

The Latest Developments In Variable Frequency Drives

A variable frequency drive can be a speed manage technique employed for regulating the speed of an alternating existing electric motor. The speed regulation is effected by varying the frequency of the electrical energy supplied to the motor. Variable frequency drives find wide application in ventilation systems for big buildings, conveyors, pumps, elevator, machine tool drives, etc.

An alternating present induction motor draws up to 6 times its rated current at the time of commence up. The existing continues to remain high till the motor approaches the full speed. When a variable frequency drive is used to begin the induction motor, a low frequency and a low voltage are applied to the motor. Typically, the start-up frequency is 2 Hz or less. As the frequency is low, the existing flow at the time of starting will also be low. When the motor is started using the variable frequency drive, the applied voltage and frequency are increased at a controlled rate to make sure that the motor does not draw excessive present. This technique of starting 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 technique consists of an AC motor, a controller and an operator interface. A controller can be a solid state electronic energy conversion device. AC input energy is converted to DC intermediate energy employing a three-phase bridge rectifier program. The DC power is then converted to quasi-sinusoidal AC power using an inverter switching circuit.

The positive aspects of a variable frequency drive are the following:

Saving in electrical power consumption is by far essentially the most essential benefit of using variable frequency drives. For instance, AC motors employed in ventilation systems are not needed to often run at peak load. Variable frequency drives save power by controlling the volume of air needed for a certain technique demand.

An induction motor using a variable frequency drive will last longer. The maintenance expenses will also be lower. Although traditional starters start off the motors abruptly, variable frequency drives gradually improve the speed to operating speed. This contributes to a reduction mechanical and electrical tension on the motor.

A variable frequency drive enables greater process manage. This is since variable frequency drives might be programmed to run the motor at the required load, cease as per requirement and apply a specified quantity of torque.

There are 3 types of variable frequency drives. These are constant voltage, constant existing and cycloconverters. One of the most important section of a variable frequency drive is the inverter circuit. These units assist enhance energy factor and lessen harmonic distortion.

Variable frequency sine wave drive using PIC to control speed of AC motor