VARIABLE FREQUENCY DRIVE

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VARIABLE FREQUENCY DRIVE INQUIRY FORM

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We are an acclaimed name engaged in offering our precious clients a superior quality range of Variable Frequency Drive that is procured from our reputed vendors of the market. The offered drive is manufactured using the best grade components and modernized. In order to ensure quality, the entire assortment is stringently tested on various parameters by the quality auditors. In addition to this, our offered range is highly praised by our prestigious clients situated all around the globe.

 

Features:

  • Compact size
  • Low power consumption
  • Long working life

 

Other details:

The variable speed drives (Inverter) are designed to operate induction motors which can be added to the existing system easily. They are available in capacities rating from fractional to 750 KW. The basic function of an inverter is to convert the 50 Hz incoming power to a variable frequency and variable voltage. The variable frequency is the actual requirement which controls the motor speed. There are three major types of inverter design available today known as current source inverters (CSI), variable voltage inverters (VVI), and pulse width modulated inverters (PWM). They are used for various applications as per the plant/process requirement. The advantages of the variable frequency drive are given below.

 

Advantages Of Variable Frequency Drive

  • With the help of variable frequency drive (VFD) step less, precise, stable and accurate variation of motor speed can be obtained.
  • Motor can be protected against over current, single phasing, earth fault and over temperature, by tripping the drive under these conditions.
  • Motor can be started smoothly, with no inrush current, no mechanical jerk and without sacrificing the starting torque.
  • Even if input power voltage is unbalanced, the output voltage of VFD is balanced, this avoids derating of motor due to unbalanced input voltage.
  • VFD frequency does not fluctuate even if mains frequency is varying, hence derating of motor due to frequency fluctuations is not required.
  • Motor can be stopped smoothly, by ramping down the VFD frequency, thus jerks to the motor and connected load, during stopping are avoided.
  • Motor can be accelerated or decelerated smoothly and at controllable rates. S-curves can be used during acceleration or deceleration. This avoids jerks to the motor and to the loads connected to it.
  • Dynamic braking provided in VFD helps in stopping the motor rapidly without mechanical jerks, as in case of rapid stopping through mechanical brakes.
  • Magnetic losses in motor can be saved, when it runs on light load, buy programming the VFD, so that its V/F reduces under light loading conditions.
  • VFD input maintains high power factor even if motor runs at light load resulting in poor power factor at its output.

 

How the disadvantages of Motor Supplied From VFD are overcome?

  • Introduction of VFD injects harmonic currents in mains. This disadvantage can be overcome by using harmonic filters, by using PWM converter in place of conventional diode rectifier, by using multi-pulse converter in place of 6-pulse converter at the input of VFD.
  • VFD output is non-sinusoidal and rich in harmonic content, it can overheat the motor. Extra-heating due to PWM waveform of output voltage of VFD, is not that prohibitive, so as to damage the motor. Even this can be avoided by providing sinus filter at the output of the VFD.
  • Introducing VFD between motor and mains leads to insertion loss of 2% to 3% as VFD itself has some losses.