Answer / darshan g

vvvf-variable voltage variable frequency drive
vvf- variable voltage frequency drive

the diffreance between this two drive is
in vvvf if u vary the voltage frequency eill also vary
but in vvf only voltage will vary..
ex:- ABB drives are vvvf drives

Answer / ravi - cement plant india

there is no drive like vvf . there is only VVVf drive are
posible in ac system.

IF we change only voltage ( no change in fq.) the generated
flux will be disturbed and can damage the insulation of
motor wdg, by overheating

VVF are short name of VVVF Drive

Answer / velu

vvvf means variable voltage variable frequency drives.ie.we
can vary the voltage & freqency thru freq converters
Ns = 120 * f /p
Ns= 120 *50 /4
6000/4 = 1500 rpm
Ns= 1500 rpm this is normal
if change the freq
120 * 40 / 4
4800 /4 = 1200
Ns= 1200 rpm
so 1500 rpm motor run at1200 rpm or below depending upon
our application
if you reduce the freq , the speed also reduce thru drives.

A variable-frequency drive (VFD) is a system for controlling
the rotational speed of an alternating current (AC) electric
motor by controlling the frequency of the electrical power
supplied to the motor.[1][2] [3] A variable frequency drive
is a specific type of adjustable-speed drive.
Variable-frequency drives are also known as
adjustable-frequency drives (AFD), variable-speed drives
(VSD), AC drives, microdrives or inverter drives. Since the
voltage is varied along with frequency, these are sometimes
also called VVVF (variable voltage variable frequency)
drives.The synchronous speed of an AC motor is determined by
the frequency of the AC supply and the number of poles in
the stator winding, according to the relation:

Answer / phani

vvvf drive means variable voltage variable frq drives.
main reason for drive use is speed variation and control
the staring inrush current,in SQ induction motors
n=120f/p.if not change the f how can change the
speed .because p are constant .
vvf means variable voltage frq drives

Answer / fadi el hage moussa

vvvf drive means variable voltage variable frq drives.

Answer / rajashekhara p

variable voltage and variable frequency drives are purely
works on below formula

Ns=120F/P

Since synchronous speed is mainly depends on motor
poles,frequency and it's applied voltage but there is also
another factor which affecting to above formula that is slip
for example.

A 4-pole motor that is connected directly to 60 Hz utility
(mains) power would have a synchronous speed of 1,800 rpm:


If the motor is an induction motor, the operating speed at
full load will be about 1,750 rpm. This rotor rpm is
slightly less than synchronous speed since the method of
torque production for an induction motor is by the presence
of slip (a difference in synchronous speed and actual
mechanical speed). Otherwise there would be no induction
and therefore no torque produced. On the other hand, if the
motor is a synchronous speed, the rotor speed can only
match the synchronous speed independent of load.

If the motor is connected to a speed controller that
provides power at 50 Hz, the synchronous speed would be
1,500 rpm:

hence we can conclude this as vvvf is a variable voltage
and variable frequency.

Answer / v.p.joshi

vvvf-variable voltage variable frequency drive
The drive is use for adjustable-speed an alternating
current (AC) vvvf drive by controlling the frequency and
voltage of the electrical power
supplied to the motor.

Answer / manas kumar behera

vvvf-variable voltage variable frequency drive
vvf- variable voltage frequency drive

the diffreance between this two drive is
in vvvf if u vary the voltage frequency eill also vary
but in vvf only voltage will vary..
ex:- ABB drives are vvvf drives

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