VARIABLE FREQUENCY DRIVES FOR ID FANS By M.PRASHANTH REDDY 08C01A1029 N.G.PRATHYUSHA 08C01A1033 Under The guidance of P.Sampurna lakshmi

OBJECTIVES OF VFD’S Energy saving in pump and fan application Better process control Speedup and slow down a machine. Inherent power factor correlation Safe acceleration Protection from over load current

FD FAN Air Preheater Dust collector Chimn ey ID fan BoilerEconomiser AIR-FLUE GAS CIRCUIT

VFD ID Fan Synchronous motor Coupling ID FAN ARRANGEMENT WITH VFD

VFD BLOCK DIAGRAM

TYPES OF VFD’S There are three types of vfd’s 1.current source inverter(CSI) 2.voltage source inverter(VSI) 3.cyclo converter Again current source inverter is classified into two types 1.Pulse width modulation(PWM) 2.Load commutated inverter(LCI )

LCI TYPE VFD In this type of drive system flow demand signal is received from the control signal due to the change in load conditions Advantages of LCI Increased motor life No limitations on no of starts No contribution of fault current

LCI TYPE VFD IS OF TWO TYPES 6 Pulse single channel 12 Pulse dual channel In a single channel type VFD the synchronous motor will have one winding whereas dual channel type VFD it will have two windings, one for each channel

CONVERTER OPERATION

LOAD COMMUTATED INVERTER The LCI is a static, adjustable frequency converter which supplies power to the synchronous motor LCI system block diagram consist of Transformer AC to DC converter Reactor DC to AC converter 3-phase synchronous motor

DUAL CHANNEL OPERATION When the motor can be made to operate in 12-pulse manner ;rather than 6-pulse,the motor harmonic losses can be subsequently reduced 12-pulse operation can be divided into 2 channels in both sides with 30 degrees phase

ADVANTAGES OF VFD UNLIMITED STARTS / STOPS SOFT START INCREASE IN MOTOR LIFE WIDE FLOW CONTROL PRECISE SPEED CONTROL HIGHLY EFFICIENT

CONCLUSION In this variable frequency drive system for flow control applications have a definite advantage in terms of substantial energy savings. Variable frequency drive has got fallowing advantages in addition to power savings: Increase motor life Unlimited number of starts