Siemens ET 200M, Manual, Page: 31 / 284

Installation
Marshalled Termination Assemblies for ET200M Remote I/O Modules
A5E00482820-12 31
2.2.2 Wiring Guidelines
Electrical Connections - Power, I/O, and network connections to a system are
completed through removable connectors.
For the analog I/O, Discrete Output 16 Channel and Relay Output 16 Channel
MTAs the interconnection cable shield must be connected to ground at the I/O
module. In environment with great EMC-load the connection made by the
connectors may not be sufficient. In this case, after removing the insulation the
shield of the cable should be clamped direct to ground. Analog I/O MTAs include
analog input, analog output, RTD input, TC input and failsafe analog input MTAs.
To ground the shield, the outer insulation must be removed to expose a section of
the shield. A shield contact element is installed below the I/O module and the
exposed shield placed inside the shield contact element. See S7-300 CPU 31xC
and CPU 31x: Installation. Reference order number A5E00105491-06.
Connectors - Power terminals are identified by a letter: L+ and M. The ground
connection is made to a Shield stud near the power connector. Signal I/O terminals
are identified by function (CH+, PWR), channel number (CH0-CH7) and polarity
(+/-).
Power and signal connectors will accept a maximum of #12 AWG / 3.3mm
2
wire ;
however, #14 AWG / 2.08mm
2
is specified throughout this manual for ease of use.
Power Monitor wiring is smaller and will accept a maximum of #16 AWG wire.
Wire Selection - Stranded wire is recommended for most connections, however,
solid wire is typically used for thermocouple extension wire. Carefully select wire
size, conductor material, and insulation. Some selection considerations are:
• Current and voltage to be carried
• Total length of each wire run
• Whether wire will be bundled or run singly
• Indoor or outdoor installation
• Temperature extremes (Use supply wires suitable for 5°C (10°F) above
ambient temperature.)
• Exposure to sunlight
• Vibration
• Types of contaminates
Note
It is recommended that crimp on ferrules with insulating collars be used to
terminate stranded field wiring.
Wire Routing and Conduit - DC wiring should be separated from AC wiring and
away from AC powered pushbuttons, alarms, annunciators, motors, solenoids, and
similar devices. Conduit and raceways are commonly used for routing panel wiring.
Wiring not installed in conduit or raceway should be clamped or supported
approximately every 12 inches (300 mm).