This document discusses variable frequency drives (VFDs) and their use in industrial settings. It describes the basic components and functioning of a VFD, including how they convert AC power to DC and then back to variable AC to control motor speed. VFDs allow motors to operate at optimal speeds, saving energy and reducing wear. The document outlines how to determine if a location would benefit from a VFD, such as if a pump valve is more than 30% closed. It provides examples of energy savings from installing VFDs on pumps. Key considerations for VFD installation include motor specifications, cable sizing, and programming start parameters. The major advantages of VFDs are energy savings, improved process control, lower maintenance needs

1. Study of VFD Installations

2. Basics Construction of VFD
 Inside the VFD there are 4 major sections:
 rectifier (AC/DC Converter),
 intermediate circuit (DC Link),
 inverter (DC/AC Converter) and
 control/regulation (for interface)

3. Working of VFD
 The operation of the drive is as follows :
Power first goes into the rectifier, where the 3-phase AC is converted into a rippling
DC voltage. The intermediate circuits then smoothes and holds the DC Voltage at a
constant level or energy source for the inverter. The last section, the inverter, uses the
DC voltage to pulse the motor with varying levels of voltage and current depending
upon the control circuit.
The control section uses the frequency, voltage and phase angle to control the inverter.

4. Function of VFD
VFD is a system for controlling the rotational speed of a motor by
controlling the frequency of the electrical power supplied to the
motor
Variable speed drives gradually ramp the motor up to operating
speed to lessen mechanical and electrical stress, reducing
maintenance and repair costs, and extending the life of the motor
and the driven equipment
Variable-frequency motors on fans save energy by allowing the
volume of air moved to match the system demand. By using VFDs
the system can maintain a constant level or pressure without
continuously cycling the pump or fan on and off. This allows for a
better system control of a level or pressure, instead of cycling
between a wide differential

5. How to analyze the necessity for VFD at a
location
We check for the pump valves that are throttled
If the valve is 30-40 % throttle (closed), then it indicates that
flow required is less
In such a case VFD can be installed, the valve can be opened
fully and fluid’s speed and flow can be controlled
For example : Back water pump 2 at PM-1, was running at 1400
rpm taking 22 kW before installation of VFD. But after VFD
installation, it consumes 12 kW while operating at 1100 rpm.

6. VFDs in Drive Room

7. VFD SHIFTING WORK IN PROGRESS VFD IN LINE

8. Wiring Diagram of Fan Pump Motor

9. VFD in Drive
Room

10. How VFD works at these locations
VFDs are installed at Fan Pump motors.
Fan pump motor responsible for providing stock to the
Head Box
Head Box requires a control of either head or level
Control of a level or pressure in Head Box is done by VFD
A reference signal is fed to the VFD and using a
comparator, an error signal is generated based on the
deviation of current value from the reference value. The
controller in the VFD, then, increases/decreases the speed
based on the signals generated

11. Head Box Pressure and Level Control
LP Air from Air Receiver
Drive End Tender End
HP Head box
LT
PT
Inlet Pulp
PV
PCV
LIC 4-20 mA
IP PIC
Air Drain
SP Air Supply 1.4
0.2 To 1 kg/cm2
kg/cm2
Fan VFD
Pump
4-20 mA
IP- Current to Pressure Converter LIC- Level Indicating Controller
SP- Set Point VFD- Variable Frequency Drive
PV- Process Value LT- Level Transmitter
PCV- Pneumatic Control Valve PT- Pressure Transmitter

12. Major Considerations while installing a
VFD
Motor Specifications
VFD Specifications
VFD input/output current
Cable Size
Starting parameters
 Motor name plate
 Reference speed
 Overload current setting
 Operating option (keypad/remote)
 V/f ratio control

13. Conclusive advantages of using a
VFD
Energy Savings
Better Process Control
Reduced Maintenance
Higher System Efficiency
Remote Mounting

14. Thank You