DC Power Plants for
                    Telecommunications and Data

                              Presented to

                           INFOBATT 2005


                              Thomas G. Croda
                               Principal Engineer


CSI Telecommunication
                                                    1
Engineers
Introduction
 Engineering Requirements
 Applicable Standards




      CSI Telecommunications
                               2
             Engineers
Engineering Considerations

Equipment to be Powered
Required Reserve Time
Minimum Operating Voltage
Size of the Facility




    CSI Telecommunications
                             3
           Engineers
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
2000 - 25,000 Amp DC Power Plant
                              Dual Level Distribution
                                                                      Shunt
                          -48 VDC
                          Return
                                                                               Primary    Secondary
     +                                   +                                    Power Bay   Power Bay
1                    24             1                    24                     600 A
                                                                                Fuses                 “A” Power
2                    23             2                    23                   1
          Battery                             Battery                         2
                                             String #N                                                “B” Power
         String #1
         1300 AH                             1300 AH
                                                                                                             To Equipment
11                   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
Load Current

 At float voltage
 At end of discharge




      CSI Telecommunications
                               6
             Engineers
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
Required Reserve Time

 Regulatory requirements
 Reliability requirements
 Economic issues




     CSI Telecommunications
                              8
            Engineers
Recharge Time

 Reliability Requirements
 Rundown Problem
 Charger sizing




     CSI Telecommunications
                              9
            Engineers
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
Plant Type

 Single or Dual Level Distribution
 Architecture
 Small plants use single level
 distribution
 Large plants use dual level
 distribution



      CSI Telecommunications
                                     11
             Engineers
DC Power – Single Point Ground

       Minimal current in framework
       Balanced distribution to cancel
       fields




            CSI Telecommunications
                                         12
                   Engineers
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
Allowable Plant Voltage Drop
2 volts - battery to load
0.25 volts - between battery and primary
distribution
1.0 volt - between primary and secondary
distribution
0.5 volts - between secondary distribution
and load bay
0.25 volts - allocated for fuse, circuit
breaker, and shunt loss
Other allocations are possible
       CSI Telecommunications
                                         14
              Engineers
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
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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Questions?




CSI Telecommunications
                         25
       Engineers

Dc power plants for telecom and data

  • 1.
    DC Power Plantsfor Telecommunications and Data Presented to INFOBATT 2005 Thomas G. Croda Principal Engineer CSI Telecommunication 1 Engineers
  • 2.
    Introduction Engineering Requirements Applicable Standards CSI Telecommunications 2 Engineers
  • 3.
    Engineering Considerations Equipment tobe Powered Required Reserve Time Minimum Operating Voltage Size of the Facility CSI Telecommunications 3 Engineers
  • 4.
    Plant Size andDesign 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.
    2000 - 25,000Amp DC Power Plant Dual Level Distribution Shunt -48 VDC Return Primary Secondary + + Power Bay Power Bay 1 24 1 24 600 A Fuses “A” Power 2 23 2 23 1 Battery Battery 2 String #N “B” Power String #1 1300 AH 1300 AH To Equipment 11 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.
    Load Current Atfloat voltage At end of discharge CSI Telecommunications 6 Engineers
  • 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.
    Required Reserve Time Regulatory requirements Reliability requirements Economic issues CSI Telecommunications 8 Engineers
  • 9.
    Recharge Time ReliabilityRequirements Rundown Problem Charger sizing CSI Telecommunications 9 Engineers
  • 10.
    Rundown Problem Theproblem 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.
    Plant Type Singleor Dual Level Distribution Architecture Small plants use single level distribution Large plants use dual level distribution CSI Telecommunications 11 Engineers
  • 12.
    DC Power –Single Point Ground Minimal current in framework Balanced distribution to cancel fields CSI Telecommunications 12 Engineers
  • 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.
    Allowable Plant VoltageDrop 2 volts - battery to load 0.25 volts - between battery and primary distribution 1.0 volt - between primary and secondary distribution 0.5 volts - between secondary distribution and load bay 0.25 volts - allocated for fuse, circuit breaker, and shunt loss Other allocations are possible CSI Telecommunications 14 Engineers
  • 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.
    Battery Disconnect Notgenerally 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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