Rs485 Connections - GE MM300 Instruction Manual

CHAPTER 2: INSTALLATION

RS485 connections

MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
Figure 2-15: Typical thermistor connection
MOTOR
Stator thermistor
To switchgear
ground bus
Control power
Figure 2-16: Typical RS485 connection
Z T (*)
OPTOCOUPLER
DATA
COM
SCADA, PLC, OR
PERSONAL COMPUTER
GROUND THE SHIELD AT THE
SCADA/PLC/COMPUTER ONLY
OR THE MM300 ONLY
(*) TERMINATING IMPEDANCE AT EACH END
(typically 120 ohms and 1 nF)
One two-wire RS485 port is provided. Up to 32 MM300 IEDs can be daisy-chained together
on a communication channel without exceeding the driver capability. For larger systems,
additional serial channels must be added. Commercially available repeaters can also be
used to add more than 32 relays on a single channel. Suitable cable should have a
– +
N L + – C +
RS485 Thermistor
CPU module
SG = Surge Ground = Functional Ground
MM300
Motor Management System
TWISTED PAIR
SHIELD
UP TO 32 MM300
OR OTHER IEDs,
MAXIMUM CABLE
LENGTH OF
Z T (*)
1200 m (4000 ft.)
ELECTRICAL INSTALLATION
– R I SG
CBCT
853743A1.CDR
MM300 IED
B1 RS485 +
OPTOCOUPLER
B2 RS485 -
B3 COMMON
IED
RS485 +
RS485 -
COMMON
IED
RS485 +
RS485 -
LAST
COMMON
DEVICE
853745A1.CDR
DATA
2–13