Siemens SIMATIC Rack PC 840 Manual page 37

Equipotential Measures
Low-impedance ground connections ensure that faults arising from external power
supply cables, signalling cables or cables to peripheral units are diverted.
Therefore connect the equipotential grounding connection on the system housing
to the central earth terminal of the cabinet or the unit, into which the computer is
fitted, in such a way that it has low impedance (large surface area, large contacts).
The minimum cross section should not be less than 5 mm
The connection is on the rear of the device and is identified by the symbol:
Connecting and Switching on the Rack PC
Before you connect the Rack PC to the mains, the peripheral units must be
connected.
1. Insert the connector cable of the peripheral units into the corresponding sockets
on the port side of the Rack PC (see Section 3.4.)
2. Once the peripheral units have been connected, the device is ready for
operation from the power supply. Connect the device to the mains; the yellow
Power LED at the front lights up. The Rack PC is now in standby mode.
3. Press the On/Off button behind the front door. The yellow and the green Power
LEDs light up. The Rack PC is in operation.
Switching off the Rack PC
Press the On/Off button behind the front door. The green Power LED goes out. To
completely separate the Rack PC from the mains, you have to remove the mains
plug.
Note
If you are working with Windows, always use Start > Shut down in the task bar
for switching off your Rack PC.
SIMATIC Rack PC 840 Manual
A5E00104826-03
Setting Up and Operating the SIMATIC Rack PC 840
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