Dc power plants for telecom and data

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Dc power plants for telecom and data

  1. 1. DC Power Plants for Telecommunications and Data Presented to INFOBATT 2005 Thomas G. Croda Principal EngineerCSI Telecommunication 1Engineers
  2. 2. Introduction Engineering Requirements Applicable Standards CSI Telecommunications 2 Engineers
  3. 3. Engineering ConsiderationsEquipment to be PoweredRequired Reserve TimeMinimum Operating VoltageSize of the Facility CSI Telecommunications 3 Engineers
  4. 4. Plant Size and Design Load current Voltage operating range Required reserve time Recharge time Battery sizing Rundown problems Allowable plant voltage drop Grounded (+) conductor CSI Telecommunications 4 Engineers
  5. 5. 2000 - 25,000 Amp DC Power Plant Dual Level Distribution Shunt -48 VDC Return Primary Secondary + + Power Bay Power Bay1 24 1 24 600 A Fuses “A” Power2 23 2 23 1 Battery Battery 2 String #N “B” Power String #1 1300 AH 1300 AH To Equipment11 12 11 12 Bays Return 14 800 Amp 800 Amp Battery Battery Charger Charger #1 #N 480 VAC 480 VAC 3 Phase 3 Phase CSI Telecommunications 5 Engineers
  6. 6. Load Current At float voltage At end of discharge CSI Telecommunications 6 Engineers
  7. 7. Voltage Operating Range See T1.315 for new equipment (40-57 VDC) Check specific equipment for its operating range Float voltage End of discharge voltage Equalize voltage CSI Telecommunications 7 Engineers
  8. 8. Required Reserve Time Regulatory requirements Reliability requirements Economic issues CSI Telecommunications 8 Engineers
  9. 9. Recharge Time Reliability Requirements Rundown Problem Charger sizing CSI Telecommunications 9 Engineers
  10. 10. Rundown Problem The problem of more load than the chargers will support What happens with a 1000 Amp load at 54 VDC? Since the entire load is "constant power" the load at 40 VDC is: 54 * 1000 / 40 = 1350 Amps The MINIMUM amount of chargers must exceed 1350A. CSI Telecommunications 10 Engineers
  11. 11. Plant Type Single or Dual Level Distribution Architecture Small plants use single level distribution Large plants use dual level distribution CSI Telecommunications 11 Engineers
  12. 12. DC Power – Single Point Ground Minimal current in framework Balanced distribution to cancel fields CSI Telecommunications 12 Engineers
  13. 13. Applicable Standards T1.311 DC Power Systems – Telecommunications Environment Protection T1.315 Voltage Levels for DC-Powered Equipment in the Telecommunications Environment NFPA 70 National Electrical Code Applicable Local Standards CSI Telecommunications 13 Engineers
  14. 14. Allowable Plant Voltage Drop2 volts - battery to load0.25 volts - between battery and primarydistribution1.0 volt - between primary and secondarydistribution0.5 volts - between secondary distributionand load bay0.25 volts - allocated for fuse, circuitbreaker, and shunt lossOther allocations are possible CSI Telecommunications 14 Engineers
  15. 15. Battery Sizing Considerations Average Discharge Current Average Discharge Voltage used for calculating Average Discharge Current 45 VDC is a good value (42- 48)/2=45VDC If the load is 1000 ADC at Float (54 VDC), the load at 45 VDC is 1000*54/45 = 1200 ADC USE THIS VALUE TO SIZE YOUR BATTERY CSI Telecommunications 15 Engineers
  16. 16. Battery Disconnect Not generally used in the telecom industry. If used, it should be 2-pole to completely isolate the battery. Each string should have a separate disconnect so one failure will not fail the plant. CSI Telecommunications 16 Engineers
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  25. 25. Questions?CSI Telecommunications 25 Engineers

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