Appendix
B
Functional Description of Operation
Page
40
8.8.1 Local RS-232 Port
A 9-pin RS-232 communication port is provided on the front of
the relay for local data readout and programming when the
communication option is installed.
Use of this port is restricted to Siemens field service and factory
personnel, and connection to this port automatically disables
remote RS-485 communications.
8.8.2 Local or Remote with Siemens
Power Monitor™ Unit
The RS-485 port permits interconnecting multiple SCOR relays,
4 700 power meters, Static Trip IIIC trip units, and other com pat
ible devices via an industry standard shielded twisted-pair EIA
RS-485 communication bus to a Siemens Power Monitor™
display and monitoring unit. A Power Monitor unit can accom
modate up to 64 devices. The bus length can be up to 4000 feet.
The Power Monitor unit is intended to be a "factory floor" tool,
and can be mounted on medium-voltage or low-voltage switch
gear, serving all circuit breakers within a substation or controlroom,
or it may be located remotely at a central maintenance/control
area.
The Power Monitor unit works intimately with SCOR relays to
provide comprehensive displays, monitoring, and logging of all
the data from all devices on the bus. It is a dedicated computer
which constantly monitors each device on the communications
bus. Every data item available from the front of the relay is also
available at the Power Monitor unit. The Power Monitor unit also
provides information not available on the SCOR display, such as
system diagrams with real-time amperes and circuit breaker
position; detailed data for all phases and ground simultaneously
which changes to a trip log with time stamped currents at the
time of trip, relay target operation plus watchdog status; a MIN/
MAX log; and an event log with a time stamped chronological
listing of events of all devices on the bus. The event log is a
powerful tool for operating and maintenance personnel.
Configuration of the SCOR relay is read and stored by the Power
Monitor unit, and the relay can be configured or changed
remotely from the Power Monitor unit (except for the tap
switches which must be set manually on the front panel).
Configuration and changes from the Power Monitor unit is
password protected.
For complete operation of the SCOR relay with a Power Monitor
unit, see the Siemens
Power Monitor™ Display and Monitoring
Unit
(Manual No. SG-401 8-01 ).
8.8.3 Local or Remote by Owner's Computer
Installations which do not have a Power Monitor unit can use a
computer equipped with Siemens Power Monitor-PC program
connected through a Siemens Isolated Multidrop™ RS-485/RS-
232 converter. If the SCOR relays and other devices are
interconnected by the communication bus described above,
the computer can access all devices, and display the same data
as described for the Power Monitor unit. This can be helpful
when initially configuring a system which has multiple devices,
and for periodic downloading of event and MIN/MAX data. For
information about operation with the Power Monitor PC, refer to
the Siemens
Power Monitor PC™ User's Guide
(Manual No. SG-
4028).
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