WISA Meeting Help

1. WISA Meeting Help • Arrange a Speaker, Write Bio, Introduce February 24, 2015 March 24, 2015 May 26, 2015 Upcoming Meetings October 28, 2014 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

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

8. 120 * Frequency # Motor Poles AC Motor Basics 2 Pole Motor Motor RPM is equal to: 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 ControlBefore 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 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 1-500 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 WhenApplying 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).