GE Industrial Solutions POWER LEADER PMCS Network Architecture Guide - Manual (Page 43)

Power Management Control System
Chapter 2 – Network Design
33
7700, according to the GE 7700 Gateway User’s Guide (DEH-
40035).
When all connections have been made and the IEDs and
software are appropriately configured, Bill applies power
to the system and runs tests to assure that everything is
functioning properly. If any difficulties are encountered,
he refers to the trouble-shooting guide in Chapter 4.
Case Five
In this case study, the circumstances are similar to those in
Case One, with the addition of several RS-485 dual-port
IEDs. The PMCS host resides on Modbus, connected to
several RS-485 Modbus segments.
The IED list is:
• One EPM 7300 Electronic Power Meter
• One Multilin SR745 Transformer Management Relay
• One Multilin SR760 Feeder Management Relay
• One Multilin 269+ Motor Relay
• One Multilin 565 Feeder Management Relay
• Two dual-port RS-485 Modbus Monitors to serve as
remote-viewing stations for the IEDs on segments 3
and 4
• One Modbus Concentrator to support the commnet
IEDs below
• One POWER LEADER Electronic Power Meter
• One Spectra Electronic Control Module
• One Enhanced MicroVersaTrip-C trip unit
He checks the list of communication protocols in Table 1
and notes that most of his IEDs communicate on Modbus,
but because he wants to use several commnet IEDs in the
Machining area, he’ll need a Modbus Concentrator. As
well, the Modbus IEDs communicate at different baud
rates, and Bill makes a note that they should be placed on
separate RS-485 networks for improved performance. He
decides to use four RS-485 networks supported by the
recommended communications card at the host PC.
Bill now turns to his floor layout to see just where the
wiring could be run and how many feet of cable will be
needed. He maps where his IEDs must be located and
where the host PC will sit. Next he measures the cable runs
required to connect the IEDs to the host PC, keeping in
mind that the wiring rules require him to daisy-chain the
IEDs on each RS-485 network one after another.
Bill calculates the cable length of each RS-485 network and
finds that none are over the 4000-foot limit, so he won’t
need to use any RS-485 repeaters. The commnet segments
are also within the wiring limits, so no POWER LEADER
Repeaters are required.
The factory floor is very large though, and Bill wants to be
able to view IED data at several locations to save walking all
the way back to his office every time he wants to check an
IED. To serve this purpose, he’s purchased a pair of dual-
port Modbus Monitors, which he will install in the Milling
and the Machining areas, respectively. He checks the
Modbus Monitor wiring rules and sees that he’ll be able to
connect RS-485 Network 3 to the RS-485 Port A of each
Monitor and RS-485 Network 4 to the RS-485 Port B of
each Monitor. This will allow him to view data from the
IEDs in these areas at either station as well as back in his
office at the host PC.
Proper termination is required at each end of the network
and is provided at the RS-485 card by placing jumpers
between the correct pins (see RS-485 card user manual).
The appropriate terminating resistors must be used at the
opposite end of each RS-485 network, per Section 2–4, rule
4.
The network architecture diagram Bill creates is shown in
Figure 27.
Bill's Office
GHO Corp Machine Shop -
network wiring diagram
350'
550'
100'
Terminating
Resistors
Multilin 565
Feeder Management Relay
at main power feed SR469
Motor
Management
Relay
SR750
Feeder Management Relay
EPM 3720
Electronic
Power Meter
Multilin 269+
Motor Relay
400'
600'
Assembly Line Area
Milling Area
Machining
Area
Lathe Area Network 4 - 19.2 kbaud
Network 3 - 19.2 kbaud
N
et
w
or
k
2
- 2
40
0
ba
ud
N
et
w
or
k
1
- 9
60
0
ba
ud
RS-485 networks
terminated at host PC
Modbus Monitor #1
RS-485
Port A RS-485
Port B
300'
Modbus Monitor #2
RS-485
Port A RS-485
Port B
Modbus
Concentrator
300'
750'
300'
550'
POW ER LEADER EPM
Spectra ECM
EMVT-C
Trip Unit
400'
250'
250'
50'
Multilin 239
Motor Protection
Relay
Figure 27. Floor layout for Case Five.
Confident that his new design will provide maximum
performance and with his wiring requirements and limits