Siemens Simatic S7-200 System Manual page 26

Installing an S7-200 Micro PLC
Guidelines for North American Installation
The following items are general wiring guidelines for installations in North America where
multiple AC voltages are present. Refer to Figure 2-14 as you read these guidelines.
Provide a single disconnect switch (1) that removes power from the CPU, all input
circuits, and all output (load) circuits.
Provide overcurrent devices to protect the CPU power supply (2), the output points (3),
and the input points (4). You may also fuse each output point individually for greater
protection.
Make AC power connections to the CPU power supply, AC output driven loads, and
relay-driven loads either line-to-grounded neutral (5) or line-to-line (6).
Connect all S7-200 ground terminals to the closest available earth ground (7) to provide
the highest level of noise immunity. It is recommended that all ground terminals be
connected to a single electrical point. Use 14 AWG or 1.5 mm
Caution
!
Line-to-line voltages in power systems with 230 VAC nominal line-neutral voltages will
exceed the voltage rating of the S7-200 power supply, inputs, and outputs.
Exceeding the voltage may cause failure of the S7-200 and connected equipment.
Do not use line-to-line connections where the voltage rating of your S7-200 module is
exceeded.
L1
L2
N
PE
Figure 2-14
2-12
120 VAC power to CPU and inputs
120 VAC and 220 VAC load outputs
(1)
(3)
(6)
(7)
DO
S7-200
DI
AC/AC/AC
AC System Installation
2
wire for this connection.
(2)
(2)
(4)
(5)
(5)
P/S
DI DO
EM221AC EM 222AC
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02