Variable speed fire pump controllers can use variable frequency drives (VFDs) to control pump speed. VFDs have several elements including rectifiers, DC links, and inverters. They provide soft starting for motors but can also affect motors and electrical systems. Proper motor requirements, testing, and system tuning are needed for fire pump applications.

1. Variable Speed Fire Pump Controllers - for - F.M. Approvals - by - James S. Nasby Columbia Engineering

3. Model ECV-250-46-* 250 Hp – Single Source A.T.L Start in Bypass

4. Model ECV-250-46-* 250 Hp – Single Source A.T.L Start in Bypass

5. Model ECVRTZ-100-46-*

6. Inside View of Drive Bay D.C. Link Reactor Line Reactor Cooler CPT & Fuses

12. System Response Curves Under Damped Oscillatory (With Overshoot) Over Damped Critically Damped

15. Power Circuit Schematic * Was Optional

16. VFD OCP Fuses and view of VFD Sans Cover

17. Schematic Diagram Single Source A.T.L. (D.O.L.) Starting in Bypass Mode Low to Moderate Horsepower Note Mechanical Interlock (Mech Intk) Between R1 and BP Contactors.

18. Line Reactor and 2nd Cooler

19. Two Coolers for 300 Hp VFD Note: this unit sees regular service a pump company pump test facility.

21. Close-up of Pressure Switch and Both Pressure Transducers

22. External Wiring Diagram

25. VFD = Motor Running Only (No Motor Starting Region) Typical Motor Torque and Pump Torque Curves

26. Lower Frequency Shortens Curve This point Moves Left Relative to Frequency 100% = 60 Hz or 59 or 30 or any Frequency

27. 3 Phase Line Freq. AC / DC Smoothing DC / AC At “X” Khz VFD – Principles of Operation Modulation Frequeny Typically 2 to 10 Khz

28. PWM Basic VFD Voltage Waveform Pulse Mode Modulation at 2.0 to 10.0 Khertz 2 Khz One Cycle

29. PWM Motor Voltage Waveform with No Filtering

30. PWM Motor Voltage Waveform with Load (Motor) Reactor

31. PWM Motor Voltage Waveform with Motor Filter

32. Motor Electrical Measurements Special Metering Required due to the High Voltage and Frequency

43. Multi-Acre Multi-Building Campus …

44. … and Back-up Distant Water Supply…

45. Lead to Multiple System Time Constants Note 253 Second Chart Span

46. Note 151 Sec. Chart Span Lead to Multiple System Time Constants

47. Note 86 Sec. Chart Span Lead to Multiple System Time Constants

48. Note 63 Sec. Chart Span Lead to Multiple System Time Constants Estimated 25s, 20s, 4s, 2s & ?? Hydraulic Time Constants

49. Unit Testing Small Unit after High and Low Temp. Testing: Ta < 0 º C and Ta > 60 º C Thermocouple Switch Box on top of unit.

50. Unit Testing

51. Unit Testing - 350 Hp Unit

52. Unit Testing - 350 Hp Unit

53. Unit Testing - 350 Hp Unit

54. Unit Testing - 350 Hp Unit

55. Unit Testing - 350 Hp Unit

56. Questions?