1. WISA Meeting Help Arrange a Speaker, Write Bio, Introduce
February 24, 2015
March 24, 2015
May 26, 2015
Upcoming Meetings
October 28, Del Tech Tour
November 25, 2014 Career Development

2. Advantages of Adjustable Speed Drives in Process Control
Motor Driven Pump Systems account for about 20% of Worldwide Energy Use
Some Plants have usage approaching 50%
Adjustable Speed Drives can Improve Process Control and Greatly Reduce Energy Costs

3. Methods of Variable Flow Control
Fans
Pumps
Damper Control
Throttling Valve Control
Inlet Vane Control
Variable Frequency Drive

4. High Percentage of Plant Connected Horsepower is for Fans and Pumps
Opportunity to save energy when you can reduce CFM or process flow rate using a variable speed drive rather than using dampers or a control valve

5. AC MOTOR
BASICS

6. Purpose of an “AC Motor”
Electrical
Energy
Mechanical
Energy
The purpose of an AC Motor is to
Convert Electrical Energy into Mechanical Energy

7. Stator Winding Assembly
AC MOTOR CONSTRUCTION
Motor Frame Assembly
Rotor
Assembly
Stator Winding Assembly

8. AC Motor Basics 2 Pole Motor Motor RPM is equal to: 120 * Frequency
# Motor Poles
Note that Frequency is the only variable to affect motor speed
Rotating Magnetic Field of a 2 Pole AC Induction Motor

9. Types of Variable Speed Control Before AC Variable Speed Drives
Control Valves, Dampers and Vanes
Fossil Fuel Engines
Eddy Current Clutches
Hydraulic Couplings
Variable Pitch Sheaves
Motor Generator Sets

10. AC Drive M Inverter - Changes fixed DC to adjustable AC
Rectifier
DC Bus
Inverter
AC Power Supply M
Rectifier
- Converts AC line voltage to Pulsating DC voltage
Inverter
- Changes fixed DC to adjustable AC
- Alters the Frequency of PWM waveform
Intermediate Circuit (DC BUS)
- Filters the pulsating DC to fixed DC voltage

11. Adjustable Speed Drive Availability
110V Single Phase Fractional HP
Medium Voltage (4160V) Thousands of HP
Most are 460Volt HP

12. Does my load profile vary sufficiently to justify a AFD?
If the Speed of the Application is constant DO NOT USE
If the load is not running at full speed for a large portion of the time then Evaluate the Use
Sweet Spot is a Variable Torque Load

13. Variable Torque Loads(Fans & Pumps)

14. Variable Torque Loads In these applications:
Torque varies directly with speed squared
Power varies directly with speed cubed
This means that at half speed, the horsepower required is approximately one eighth of rated maximum

15. Variable Speed Horsepower Requirements
Flow proportional to speed Q1/Q2= n1/n2
Then: HP2/HP1= (n2/n1)3
Therefore: HP2=HP1(n2/n1)3
At 80% Speed, HP=(.80)3 = .512

16. Advantages of a Adjustable Speed Drive
1. Energy savings on fan and pump applications
2. Better process control and regulation
3. Speeding up or slowing down a machine or process
4. Inherent power-factor correction
5. Elimination of Other Mechanical Control Devices

17. Some Considerations When Applying ASD to AC Motors
Thermal considerations of motor operation with a VFD
should be one of the first areas of attention for successful
application.
The ability of a motor to cool itself effectively is reduced as the motor is slowed down. Over-sizing the motor or providing external forced air ventilation may be required with extended operation at low speeds and high loads.
Operation at different speeds can cause mechanical resonances in driven equipment. These speeds should be identified and programmed out of the motor’s operating range.

18. ASD Considerations
ASD’s generate harmonic voltages and currents which can, in some cases, cause undesirable effects on the electrical distribution system and affect equipment operation.
Longer Cable Lengths can cause a voltage reflection of up to two times the applied voltage due to standing waves or a ‘‘ringing effect’’, and becomes more problematic with longer cable runs (typically greater than 15 m or 50 feet).