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December 18, 2019

Today the VFD is perhaps the most common type of output or load for a control program. As applications become more complex the VFD has the capacity to control the speed of the engine, the direction the electric motor shaft can be turning, the torque the electric motor provides to lots and any other motor parameter which can be sensed. These VFDs are also obtainable in smaller sized sizes that are cost-efficient and take up much less space.

The arrival of advanced microprocessors has allowed the VFD works as an exceptionally versatile device that not merely controls the speed of the electric motor, but protects against overcurrent during ramp-up and ramp-down conditions. Newer VFDs also provide ways of braking, power enhance during ramp-up, and a number of controls during ramp-down. The largest financial savings that the VFD provides is definitely that it can ensure that the electric motor doesn’t pull excessive current when it starts, therefore the overall demand element for the whole factory could be controlled to keep carefully the utility bill only possible. This feature by itself can provide payback more than the price of the VFD in under one year after purchase. It is important to keep in mind that with a traditional motor starter, they will draw locked-rotor amperage (LRA) when they are starting. When the locked-rotor amperage happens across many motors in a manufacturing facility, it pushes the electrical demand too high which often results in the plant having to pay a penalty for all the electricity consumed during the billing period. Since the penalty may end up being as much as 15% to 25%, the cost savings on a $30,000/month electric variable speed gear motor china expenses can be used to justify the buy VFDs for virtually every motor in the plant even if the application may not require operating at variable speed.

This usually limited the size of the motor that may be controlled by a frequency and they were not commonly used. The earliest VFDs used linear amplifiers to control all aspects of the VFD. Jumpers and dip switches were used provide ramp-up (acceleration) and ramp-down (deceleration) features by switching larger or smaller resistors into circuits with capacitors to make different slopes.

Automatic frequency control consist of an primary electric circuit converting the alternating current into a direct current, after that converting it back into an alternating current with the required frequency. Internal energy loss in the automatic frequency control is rated ~3.5%
Variable-frequency drives are trusted on pumps and machine tool drives, compressors and in ventilations systems for huge buildings. Variable-frequency motors on enthusiasts save energy by allowing the volume of air moved to match the system demand.
Reasons for employing automatic frequency control can both be related to the features of the application and for saving energy. For instance, automatic frequency control can be used in pump applications where the flow can be matched either to quantity or pressure. The pump adjusts its revolutions to a given setpoint with a regulating loop. Adjusting the circulation or pressure to the real demand reduces power consumption.
VFD for AC motors have been the innovation that has brought the use of AC motors back into prominence. The AC-induction engine can have its rate transformed by changing the frequency of the voltage used to power it. This implies that if the voltage put on an AC electric motor is 50 Hz (found in countries like China), the motor works at its rated velocity. If the frequency can be improved above 50 Hz, the electric motor will run faster than its rated speed, and if the frequency of the supply voltage is definitely significantly less than 50 Hz, the engine will operate slower than its ranked speed. According to the adjustable frequency drive working theory, it’s the electronic controller specifically designed to modify the frequency of voltage provided to the induction motor.