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Installing and connecting the device
3.3 Connecting the device
SIMATIC IPC627D/827D
Operating Instructions, 09/2014, A5E32990859-AB
37
3.3.4
Connecting the 24 VDC power supply
Note before connecting the device
WARNING
Safety extra-low voltage (SELV)
The device should only be connected to a 24 V DC power supply which meets the
requirements of safe extra low voltage (SELV) according to IEC/EN/DIN EN 60950-1. A
protective conductor must also be used. The conductors must withstand the short-circuit
current of the 24 V DC power source, so that a short-circuit will not damage the cable. Only
connect cables with a minimum cross-section of 1.3 mm
2
(AWG16) and a maximum cross-
section of 3.3 mm
2
(AWG12).
Note
The 24 V DC power source must be adapted to the input data of the device (see
specifications).
Procedure
1. Make sure that the ON/OFF switch is in the posi-
tion "0" (OFF) to prevent unintentional startup of
the device when it is connected to the 24 V power
supply.
2. Switch off the external 24 V DC power supply.
3. Connect the 24 VDC plug connector to the device.
Observe the correct polarity of the contacts:
①
DC 24 V
②
ground
③
protective conductor
4. If necessary, install the enclosed cable grip.
5. Secure the 24 VDC cable to the cable grip using a
cable tie.
Note
Reverse-polarity protection
The DC power supply (24V) has a mechanism to protect against reverse polarity. In the
event that the 24 VDC lines are reversed (24 VDC nominal (-20% / +20%) and connected to
ground, the device will not be damaged. The device will simply fail to turn on. After the power
supply has been connected correctly, the device will again be ready to operate.