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NON-AGENDA

APPLICATION OF MOTORS TO ADJUSTABLE FREQUENCY DRIVES PART 1 Alan Lowe, Senior Electrical Consultant. NON-AGENDA. RISE TIMES REFLECTED WAVES BEARING CURRENTS CABLE SELECTION IGBT. AGENDA. INTRODUCTION NOMENCLATURE WHY USE AFD HORSEPOWER, SPEED, TORQUE MOTOR CAPABILITIES & LIMITATIONS

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NON-AGENDA

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  1. APPLICATION OF MOTORS TO ADJUSTABLE FREQUENCY DRIVESPART 1Alan Lowe, Senior Electrical Consultant

  2. NON-AGENDA • RISE TIMES • REFLECTED WAVES • BEARING CURRENTS • CABLE SELECTION • IGBT

  3. AGENDA • INTRODUCTION • NOMENCLATURE • WHY USE AFD • HORSEPOWER, SPEED, TORQUE • MOTOR CAPABILITIES & LIMITATIONS • TYPES OF LOADS

  4. PRE-TEST

  5. A “SPECIAL” MOTOR WILL BE REQUIRED FOR DRIVE APPLICATIONS: ALWAYS MOST OF THE TIME RARELY NEVER

  6. A MOTOR APPLIED TO AN AFD MUST MEET WHICH OF THE FOLLOWING: NEMA M-G 1 PART 30 NEMA M-G 1 PART 31 IEEE 841 NEMA PREMIUM EFFICIENCY

  7. OPERATING ON AN AFD A 100 HP, 1200 RPM MOTOR CAN DELIVER 100 HP • BETWEEN 1200 AND 1500 RPM • BETWEEN 600 AND 1200 RPM • ALL OF THE ABOVE • NONE OF THE ABOVE • DON’T ASK ME—I JUST CAME FOR LUNCH

  8. DRIVE NOMENCLATURE IS IT--- VSD, ASD, VFD, OR AFD ?

  9. DRIVE NOMENCLATURE VARIABLE VS. ADJUSTABLE THE WEATHER OUTSIDE IS VARIABLE THE TEMPERATURE IN YOUR HOME IS ADJUSTABLE

  10. DRIVE NOMENCLATURE “SPEED” VS. “FREQUENCY” THERE ARE MANY KINDS OF ADJUSTABLE SPEED DRIVES: • DC MOTORS • CONE PULLEYS • STEAM TURBINE • MECH. DIFFERENTIALS • EDDY CURRENT CLUTCHES • ADJUSTABLE VOLTAGE DRIVES • ADJUSTABLE FREQUENCY DRIVES

  11. DRIVE NOMENCLATURE BE CAREFUL-- “DRIVE” CAN MEAN ALMOST ANYTHING

  12. DRIVE NOMENCLATURE DRIVE: THE EQUIPMENT USED FOR CONVERTING AVAILABLE ELECTRICAL POWER INTO MECHANICAL POWER SUITABLE FOR THE OPERATION OF A MACHINE. A DRIVE IS A COMBINATION OF A POWER CONVERTER (CONTROL), MOTOR, AND ANY MOTOR MOUNTED AUXILIARY DEVICES.

  13. WHY USE AN AFD? • THE PROCESS REQUIRES IT • THE PROCESS CAN BE IMPROVED BY IT • ENERGY SAVINGS • EASIER ON DRIVEN EQUIPMENT

  14. WHY USE AN AFD? ACCELERATION OF HIGH INERTIA LOAD TO AVOID FREQUENT MOTOR STARTING AS A REPLACEMENT FOR GEARING

  15. WHY WORRY ABOUT THE MOTOR? WHAT’S DIFFERENT? • CAN THE MOTOR PRODUCE THE REQUIRED TORQUE THROUGHOUT THE OPERATING SPEED RANGE? • WILL THE MOTOR HAVE ADEQUATE COOLING AT LOW SPEEDS? • WILL HARMONICS FROM THE DRIVE CAUSE THE MOTOR TO OVERHEAT?

  16. WHY WORRY ABOUT THE MOTOR? WHAT’S DIFFERENT • WILL THE MOTOR FLY APART AT OVERSPEED? • WILL THE DRIVE VOLTAGE WAVEFORM DAMAGE THE MOTOR WINDINGS? • WILL THE DRIVE VOLTAGE WAVEFORM DAMAGE THE MOTOR BEARINGS?

  17. IT’S A DRIVE SYSTEM !

  18. THE MOTOR WHAT DO WE MEAN BY A 100 HP, 1800 RPM MOTOR?

  19. HORSEPOWER

  20. MOTOR HORSEPOWER 33,000 FT-LBS/MIN 550 FT-LBS/SEC 746 WATTS / MOTOR EFFICIENCY 1 HP MOTOR

  21. MOTOR HORSEPOWER

  22. MOTOR HORSEPOWER

  23. MOTOR HORSEPOWER Generally a motor can deliver: • Rated TORQUE at and below base rated speed. • Rated HORSEPOWER at and above base rated speed. But there are some LIMITATIONS!

  24. NEMA MG-1 Part 30.2 GENERAL PURPOSE MOTORS USED WITH ADJUSTABLE-VOLTAGE OR ADJUSTABLE-FREQUENCY CONTROL OR BOTH Part 31 DEFINITE PURPOSE INVERTER FED POLYPHASE MOTORS

  25. LIMITATIONS: REDUCED COOLING 1.15 S.F. 1.0 S.F. MOTOR NEMA MG-1 FIGURE 30-2

  26. LIMITATIONS: HARMONIC HEATING IT DEPENDS ON THE MOTOR. IT DEPENDS ON THE DRIVE. THERE’S NO ESTABLISHED METHOD OF CALCULATION. NEMA MG-1 FIGURE 30-3

  27. MOTOR TORQUE vs. SPEED RATED TORQUE = HP x 5252 / RPM

  28. MOTOR TORQUE vs. SPEED LRT per NEMA MG-1 12.38.1 TABLE 12-2

  29. MOTOR LOCKED ROTORTORQUE

  30. MOTOR TORQUE vs. SPEED P.U. TORQUE per NEMA MG1, 12.40.1

  31. MOTOR PULL UP TORQUE NEMA MG-1 12.40.1 PULL UP TORQUE FOR DESIGN A AND B MOTORS

  32. MOTOR TORQUE vs. SPEED BD TORQUE per NEMA MG1, 12.39.1

  33. MINIMUM BREAKDOWN TORQUE PER NEMA MG-1 12.39.1 FOR DESIGN A & B MOTORS

  34. BREAKDOWN TORQUE BREAKDOWN TORQUE IS PROPORTIONAL TO (V/HZ)2 ABOVE BASE SPEED BREAKDOWN TORQUE IS PROPORTIONAL TO (1/HZ)2 STARTING WITH 175% AT 60 HZ YIELDS 77.7% RATED TORQUE AT 90 HZ.

  35. LIMITATIONS: TORQUE B.D. TORQUE = 77.7% TR 2/3TR x 3/2SR = HPR NEMA MG-1 FIGURE 30-4

  36. TORQUE vs. SPEED

  37. TORQUE vs. SPEED ON AFD

  38. TORQUE vs. SPEED ON AFD

  39. TORQUE vs. SPEED ON AFD

  40. MOTOR TORQUE vs. SPEED

  41. MAXIMUM SAFE SPEED

  42. LIMITATIONS: MAX SAFE SPEED ALLOWABLE OVERSPEED OPERATION BASED ON NEMA MG 1 TABLE 30-1

  43. LOAD CHARACTERISTICS VARIABLE TORQUE CONSTANT TORQUE CONSTANT HORSEPOWER

  44. VARIABLE TORQUE LOAD CENTRIFUGAL PUMPS FANS

  45. VARIABLE TORQUE LOAD AFFINITY LAWS FOR CENTRIFUGAL PUMPS

  46. VARIABLE TORQUE LOAD

  47. VARIABLETORQUE LOAD

  48. VARIABLETORQUE LOAD 102% LOAD @ 65 HZ

  49. SELECT MOTOR FOR VARIABLE TORQUE LOADS MAKE SURE THE MOTOR CAN OPERATE SAFELY AT THE TOP SPEED REQUIRED BY THE LOAD. MAKE SURE THE MOTOR CAN DELIVER THE REQUIRED HORSEPOWER AT THE TOP SPEED. LOW END OPERATION IS NOT A PROBLEM.

  50. CONSTANT TORQUE LOADS CONVEYORS POSITIVE DISPLACEMENT PUMPS CRANES PAPER MACHINE SECTIONS

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