American Audio VELOCITY - REV 4-05 Betriebsanleitung PDF herunterladen (Seite 151)

METRO RAIL DESIGN CRITERIA SECTION 9 / SYSTEMS

DE304.09 9-146 Revision 4 : 05/09/12

Metro Baseline Re-Baseline: 04/29/10

2. The cables shall have sufficient conductivity to maintain traction power

voltage levels within the limits defined, confining the major voltage drop to

wayside distribution system, rather than permitting excessive voltage drop in

the connecting cables.

3. Traction power feeders for each power zone shall have cable capacity as

required by the ratings of the associated DC feeder circuit breakers. These

ampacities shall not be compromised by virtue of different types of raceway

arrangements for various sections of the feeder.

4. Negative return cable shall be provided between the substation negative bus

and the connection to each pair of running rails.

5. Since both the contact rail and the OCS constitute a vibrating mass,

provision shall be made in the design of all cable terminations to prevent

cable failures. The design shall utilize standard stranding feeder cables with

a transition to extra-flexible stranding cables being provided for the final

connection to the wayside distribution system.

6. Feeders shall be of a common conductor size, using multiple conductors for

the different ampacities.

7. Cables shall be insulated, non-shielded, single conductors suitable for use in

wet or dry locations and rated 2,000 Vdc, 90

C conductor temperature for

normal operation. The conductors shall be copper with class C or D

stranding, conforming to ASTM B8, with EPR insulation and low smoke

jacket.

8. Cables from the substation to the OCS/contact rail shall not be spliced.

9. Traction power positive cables from the DC feeder breaker connections and

negative cables from the negative bus connections shall be laid or run in

appropriate raceways such as conduits, trays, cable trenches, or on racks

through the substations. Such raceways shall provide an adequate cross-

sectional area to permit a neat alignment of the cables and to avoid crossing

or twisting single layer.

Positive and negative cables shall be run in separate raceways.

10. On racks, porcelain insulators designed for such purpose shall be used in

the supporting arms. Such supporting arms or racks shall be spaced to avoid

excessive weight or pressures against the cable insulation.

11. The ends of all exposed conduits shall be sealed.

12. All conduit stub-ups shall be protected against damage during construction

operations.

13. Feeder ductwork shall be buried underground and shall consist of polyvinyl

chloride (PVC) conduit encased in concrete. Design of ductwork such as

conduit size, design cable pull, maximum total angular turn, and minimum

embedment depth below grade, manhole spacing and duct gradient shall be

in accordance with NEC requirements. Feeder ductwork shall be identified

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