Connection Cables And Power Supply - Beckhoff CP39 Series Manual

4.3.4

Connection cables and power supply

Incorrect connection procedure
Incorrect procedure when connecting the cables and the power supply can cause hardware damage.
• Follow the documented procedure for connecting the cables and the power supply.
• Always connect all cables first and only then switch on the power supply.
• Please read the documentation for the external devices prior to connecting them.
Connection cables
Make sure that you first ground the panel (see chapter 4.3.1 Grounding the control panel [} 35]) and then
plug in all data transmission cables.
Lay the cables in the mounting arm adapter as shown in chapter 4.3.2 Routing the cables in the mounting
arm adapter [} 36] and then plug in all data transmission cables.
Check the screw connections between the plugs and sockets.
When connecting the control panel to an industrial PC with UPS output, we recommend using this for the
connection. In the case of CP-Link 4, we recommend connecting the CU880x transmitter boxes to the UPS
output of the PC.
Connecting the power supply
Cables with a maximum cable cross-section of 4 x 0.75 mm
For long supply lines, use 4 x 0.75 mm
should be at least 22 V at the voltage connector of the control panel, so that the panel remains switched on
during voltage fluctuations.
Proceed as follows to connect the 24 V
1. Check the correct voltage of your external power supply.
2. Plug the voltage connector into the voltage socket on the panel.
3. Screw the voltage connector to the voltage socket. Then check the screw connection.
4. Connect the panel to your external 24 V power supply.
5. Switch on the 24 V power supply.
6. Calculate the voltage at the power supply plug.
In order to check the voltage at the power supply plug, you must first calculate the voltage drop on the supply
cable. You can orient yourself to the following calculation example:
• CP3924-0000
• Power consumption: 34 W
• Current consumption: 34 W / 22 V = 1.5 A
• Connection with 10 m two-core 0.75 mm
20 m
• Constant of specific resistance of pure copper: 0.0178 Ohm * mm
• Resistance of the supply line: 0.0178 ohm*mm
With the listed data, you can now calculate the voltage drop on the supply line:
• 1.5 A * 0.475 Ohm = 0.7 V
With a CP39xx-0010 with CP-Link 4 and CU8802 transmitter box or PCIe module, the power consumption
increases. In this case, orient yourself to the following example:
• CP3924-0010
• Power consumption: 40 W
• Current consumption: 40 W / 22 V = 1.8 A
CP39xx
NOTE
2
can be used for connecting the power supply.
2
cables to achieve a low voltage drop on the supply line. There
power supply unit:
DC
2
cable, where the supply cable length then corresponds to
2
/m * 20 m / 0.75 mm
Version: 3.6
Commissioning
2
/ m
2
= 0.0178 * 20 / 0.75 = 0.475 ohm
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