American Audio VELOCITY - REV 4-05 Betriebsanleitung PDF herunterladen (Seite 146)

METRO RAIL DESIGN CRITERIA SECTION 9 / SYSTEMS

DE304.09 9-141 Revision 4 : 05/09/12

Metro Baseline Re-Baseline: 04/29/10

6. The Rectifier Unit and the DC Distribution Switchgear shall be provided with

DC ground protection of a high resistance type for the Heavy Rail TPSSs.

The Rectifier Cubicle and the DC Distribution Switchgears will be insulated

at 1,000 V level from the floor where they are installed and shall be

respectively provided with separate individual ground relays. Ground faults

on the Rectifier Unit shall trip the associated AC breaker, as well as the

associated positive breaker. Ground faults on the DC Distribution Switchgear

shall trip the respective AC breaker(s), positive breaker(s), and all its feeder

breakers.

7. The DC feeder circuit breakers of adjacent TPSS connected to the same

OCS/Third Rail section shall be provided of a transfer trip system. Each

breaker shall send transfer trip signal to the adjacent breaker whenever a

fault is detected, including over-current, rate of rise, and ground faults. The

over-current and rate of rise transfer trip signals shall allow the re-closure of

the adjacent breaker, while the ground fault transfer trip signals shall lock-

out the adjacent breaker, without any re-closing attempt.

8. A Negative Ground Device shall be provided to automatically connect the

negative bus of each substation to ground, in case the voltage to ground

exceeds a pre-set value.

9. Surge Arrestors shall be provided on the load side of each DC feeder

breaker, and shall be connected with insulated cables to grounding rods

independent from the main substation rounding grid.

10. The positive breakers shall be provided with reverse current protection.

11. All Substations shall be provided with a grounding grid with a minimum of 5

ohms resistance to ground. The grounding grids shall also meet the

requirements of the Utilities and provide safe step-and-touch potentials

according to the applicable Codes and Standards. All non-current carrying

structures and equipment enclosures shall be solidly connected to the

grounding grid, except the DC Enclosures for the rectifiers and DC

Switchgears, as required by their specific method of grounding – low

resistance or high resistance.

12. The negative return of the Mainline and Yard traction power system shall not

be grounded intentionally at any point, either at the substations, feeder

cables, or at track level.

13. The Shops shall have separate and independent TPSSs solidly grounded

and isolated from the Yards on the positive side by non-bridging section

insulators, and on the negative side by Rail Insulated Joints, properly aligned

with the respective section insulators.

G. Substation Operation

All TPSSs shall be designed for unattended operation and remote control by the

Rail Operation Control-ROC. All circuit breakers shall be able to be both locally

and remotely operated and a Local/Remote Switch shall be provided at each

TPSS. Open/close commands and open/close indications shall be provided. All

protective and supervisory devices shall be individually alarmed both locally and

remotely. Voltage and current meters shall also be provided locally and/or

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