VFD – variable frequency drive..
VFD is useful in energy saving because it reduces the
motor speed as demand decreases.When the speed is reduced
the power consumption Will also reduce because ,
Power = (speed)3 {cube of speed}
For example if the speed is reduced to 80% of the maximum
value the power consumed will be reduced by 50%
Power consumed = (0.8)3 = 0.512 = 51.2%
VFD drive controll speed of motor by varing its freq.
But at varing freq. it have to maintain V/F ratio
constant.So for reducing speed it have to reduce freq.but
its also maintain V/F ratio constant.So automatically its
voltage is reduced.
So powre is depends on V, I & PF. So its save energy..
vfd drive works almost t unity pf. so this mainly it saves
energy. if u connect motor directly it works on .8 of pf.
but vfd mainly used for better speed and torque control not
for power saving purpose
Practically VFD helps to save enery in Variable torque
loads only like Fan , pump. With affinity laws Power
proportinal to cube of speed, so if speed is reduced you
will get energy saving by using this law.
For constant torque application , if your process speed is
not full RPM but less than that say 30 Hz , then energy
saving will be there by using VFD, as you are not required
to run the motor at full speed.
have anybody checked the input and out current of drive if
yes then he knows that ipput current of drive is less than
that of out put current that is because of power factor
vfd is help to reduce the power consumption and saving the life time is motor and other related pats of the pump.basically vfd is control the motor speed and its give command to the motor as a demand
The real saving is observed when the VFD is used on input reference of temperature, pressure, differential pressure etc.,and this is more significant in case of Fans and Pumps, specially when we calculate the energy consumption over a certain period of time where different temperature and seasons are involved.
2. If 8.35%Z means the percentage impedance of 132/11kV
transformer self,will like to reconfirm the percentage
impedance that is supplied from power company?
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