American Audio VELOCITY - REV 4-05 Operations Instructions download pdf (Page 184)

METRO RAIL DESIGN CRITERIA SECTION 9 / SYSTEMS

Appendix B

DE304.09 Appendix 9B-1 Revision 1 : 05/09/12

Metro Baseline Re-Baseline: 04/20/10

1 SCADA RTU Interface Requirements

This section describes the interface requirements between the SCADA RTU subsystem and

external equipment.

1.1 General Interface Requirements

The SCADA RTU shall be the gateway for all indication and control interfaces to ROC. Data

acquisition shall be implemented using a combination of in-rack I/O modules, distributed remote

I/O and local subsystem communications links.

Interlocks shall be implemented in subsystem controls to prevent unsafe or destructive remote

operation of equipment.

Interlocks shall be implemented in the field device control circuits and shall not be implemented

in PLC logic except where approved by Metro.

1.2 Discrete Indications

Each indication from external subsystems and equipment shall be in the form of an isolated dry

contact rated at no less than 200VDC at 2 amperes.

One unshielded twisted wire pair between the subsystem control circuit and the SCADA PLC

CIC or MDF shall be provided for each discrete indication.

The SCADA RTU shall provide 24VDC class-B wetting voltage current limited to 2 amperes on

one wire in the pair and sense the return on the other wire. Indications shall function properly

regardless of polarity; however, polarity shall be consistently wired system-wide.

Unless otherwise specified or approved by Metro, all indicating relays shall be normally de-

energized.

Unless otherwise specified or approved by Metro, all indications shall utilize the relay normally

open contact.

Unsupervised indication relays for fire life safety and security functions shall be normally

energized.

1.3 Discrete Controls

Unless otherwise specified or approved by Metro, all discrete controls shall be a momentary dry

contact closures.

One unshielded wire pair shall be provided for each discrete control.

Control voltage shall be limited to 48VDC.

Subsystem control circuits shall implement any necessary interposing and seal-in (set) relays

and reset relays so that a reset of the SCADA RTU does not affect the control state of field

equipment.

1 2 ... 179 180 181 182 183 184 185 186 187 188 189 190 191

No comments

American Audio VELOCITY - REV 4-05 Operations Instructions Page 184