Nortel Networks 411-2021-111 manual System power protection, Grounding UL/CSA approval

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5-6Power and Grounding Requirements

System power protection

There are three levels of protection at a Metrocell cell site. The first level is at the power plant which may consist of a hydraulic-magnetic breaker or slow- blow fuse. This stage is not provided by Nortel. The second level of protection is located in the RIP of the frames that consists of a magnetic breaker. In some cases, a third level of protection is implemented in the equipment shelf such as the TRU/DPA shelf fans and the ATC shelf and usually consists of a faster blow fuse. This arrangement isolates faults that occur lower down in the hierarchy from affecting circuits higher up.

Grounding

UL/CSA approval

The North American electrical codes require that there be no current over the grounding conductors (see C22.1 par 10-200 and ANSI/NFPA No. 70 article 250-21) and the safety standards specify that the electrical codes be adhered to. The Metrocell uses a two-wire DC power distribution scheme. In a grounded two-wire system, the return and ground are multiply connected and an unspecified amount of the return current can flow over the grounding conductors in violation of the electrical code rules.

Therefore, each cell site has to be inspected by a safety authority (UL/CSA in North America) such that the codes requirements (refer to UL-1459 par 14.2 and 34.6 and CSA C22.2 No. 225 par 4.5.3.1a) are met in order to obtain an approval from that authority.

UL-1459 par 14.2

A product intended for permanent connection to the branch-circuit supply shall have provision for the connection of one of the wiring methods in accordance with the National Electrical Code, ANSI/NFPA No. 70.

UL-1459 par 34.6

A field-wiring terminal intended solely for connection of an equipment- grounding conductor shall be capable of securing a conductor of the size rated for the application in accordance with the National Electrical Code ANSI/ NFPA No. 70.

CSA C22.2 N0. 225 par 3.5.3.1a

Permanently connected equipment shall be provided with wiring terminals or leads for the connection of conductors not less than 14 AWG and having an ampacity not less than 125% of the rated input current.

UL would not accept the grounding of the battery return when the battery/cell site configuration is not in the same room unless the battery is floating. A dedicated battery/cell site configuration residing in the same equipment room would not raise any concerns. CSA would have no objections to a grounding

411-2021-111 Standard 01.01 June 1996

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Contents DualMode Metrocell Page Page Publication history JuneContents Datafilling a Metro Cell Site Power and Grounding RequirementsCell Site Components AppendicesBlock diagram of a 120 Stsr Metrocell using one RF Frame List of tablesPage About this document Intended audience for this publicationHow this publication is organized Applicability of this publicationCarrier RF List of termsBand DBW CellDBm DuplexerIsolation FilterForward path LossDqpsk ModulationOmni Return lossSectorization Signal RFSector Stsr Introduction Northern Telecoms DualMode MetrocellSystem architecture of a DualMode Metrocell Digital ready cellular productBasic components of a DualMode Metrocell Universal CE Frame Metro RF FrameChannel assignment Band a 416 channels Band B 416 channels 800 MHz cellular bandChannel assignment for 800 MHz cellular systems Introduction 6Introduction Standard 01.01 June Overview Cell Site ConfigurationsOmni configuration Sectorized configuration Omni N=7 frequency reuse plan120 N=7 sectorized frequency reuse plan 60 N=4 sectorized frequency reuse plan Omni cell site configuration Cell Site LayoutsControl Channel redundancy RF FrameCell Site Layouts 4Cell Site Layouts Transmit cabling TRU/DPA6Cell Site Layouts No. Receive cablingComponent requirement Frames TRUs ATCsStsr cell site configuration CE Frame Block diagram of a 120 Stsr Metrocell using one RF Frame RF FrameBlock diagram of a 120 Stsr Metrocell using three RF Frames 12Cell Site Layouts DPA 9 Port1 CCH ATC3 Port DPA 10 Port1 14Cell Site Layouts TRU/DPA ATC 16Cell Site Layouts Sector Sector Y Sector ZSector Y TX/RX, 3 RX Sector U Stsr cell site connectionControl Channel Locate Channel Receiver Sector Sector W22Cell Site Layouts Block diagram of a 60 Stsr Metrocell with two RF Frames 24Cell Site Layouts Block diagram of a 60 Stsr Metrocell with four RF Frames 26Cell Site Layouts Transmit cabling 28Cell Site Layouts TRU/DPA 30Cell Site Layouts Port2 ATC3 Port DPA Port1 RF Frame 32Cell Site Layouts Receive cabling 34Cell Site Layouts Sector Y 36Cell Site Layouts Component requirement 38Cell Site Layouts Standard 01.01 June Cell Site Components Major components of a DualMode Metrocell DescriptionNTAX98AA FRU Customer Service Operations 4Cell Site Components Standard 01.01 June Power and Grounding Requirements Safety requirementsPower and grounding requirements Power and Grounding Requirements 4Power and Grounding Requirements Frame power distribution Power distribution for the CE and RF Frames in a MetrocellSystem power protection Grounding UL/CSA approvalCEC par DC coupled signals Cable Identification 10Power and Grounding Requirements Standard 01.01 June Datafilling a Metro Cell Site Datafill OverviewTable Clli Table AcualmCavities Fan Pwr Alarm PointsMetro RF Frame ATC Hsmo +27V a Port # Rip Connector J206Table VCHINV, CCHINV, Lcrinv Frequency Assignment Example Example of Metro TRU datafillExample of Metro ICRM/TRU hardwire configuration Icrm8Datafilling a Metro Cell Site Standard 01.01 June Radio Frequency Appendix a DualMode Metrocell Cell Site SpecificationsSystem Configuration Alarms Audio InterfaceMechanical DC Power RequirementsPower Distribution Requirements Packaging EnvironmentalTelecom Compliance Regulatory Electromagnetic EmissionsRadiated Emissions Product Safety Appendix B Frequency Plans =7 Frequency plan Band a=7 Frequency plan Band B =4 Frequency plan Band a =4 Frequency plan Band B10Frequency Plans Standard 01.01 June Page Cell Site Description
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