GE Industrial Solutions POWER LEADER PMCS Network Architecture Guide - Manual (Page 16)

Power Management Control System
Chapter 1 – Introduction
6
1–6 Time & Date Stamping
PMCS stamps each event with a time and date code for
precise reference. The time and date are set by the DDE
Server and passed across the network to each IED, so that
all IEDs are synchronized.
Additionally, some PMCS IEDs support IRIG time
synchronization. If IRIG is used in a PMCS system, it is
recommended that the host PC be IRIG time synched as
well to maintain synchronization between the IEDs and
the PMCS DDE Server.
1–7 Remote System Operation
PMCS also offers the ability to use modems to reach across
wide areas to remote facilities or substations. For instance,
you could use PMCS at a central location to collect power
management data from IEDs in a factory, warehouse, or
substation in another state or control the lights, air
conditioning, or protective relays in your facility from
across the country.
An example of this scenario is shown in Figure 5.
RS-485 wiring
Modbus
device
Modbus
device
RS-232/RS-485
Converter
Host
...
Mo de m
Radio Frequency transmission,
Fiber optic connection,
Leased line
or phone line connection
Mo de m
RS-485 wiring
RS-232/RS-485
Converter
RS-232 wiring
RS-232 wiring
Figure 6. Example of remote operation using modems.
56kbps phone modems, radio frequency (RF) modems,
and fiber optic modems (FOM) may be used with PMCS.
While it is possible to use dial-up lines to connect to distant
RS-485 networks, the vagaries of the phone system and the
excessive long-distance charges preclude using this as a
twenty-four-hour-a-day connection. Leased lines dedicated
to this purpose provide a viable alternative to a constant
long-distance telephone connection.
For further information on using modems for long-range
operation of PMCS, contact your GE sales representative.