NORD Drivesystems BU0220 - Manual (Page 20)

PROFIBUS DP – Supplementary manualfor NORD Frequency Inverter SK 2xxE
20 Subject to technical amendments BU 0220 GB-0912
2.2.2 Control connections
The PROFIBUS DP modules must be provided with a 24V DC (±20%, 100mA) control voltage. Wire end
sleeves must be used for flexible cables.
Name Data
Rigid cable cross-section 0.14 … 2.5mm²
Flexible cable cross-section 0.14 … 1.5mm²
AWG standard AWG 26-14
Tightening torque (for screw terminals) 0.5 … 0.6Nm
Within the terminal box (unshielded cable section) the data cables (e.g. PROFIBUS DP, system bus) must be
installed as short as possible and of equal length. Associated data cables (e.g.: Sys+ and Sys-) must be
twisted.
NOTE
The PROFIBUS DP is already installed in the customer unit with voltage isolation from the
other signal connections.
In case of EMC problems, voltage separation of the field bus supply, the digital inputs and
system bus interface and for the external technology unit also for the two additional digital
outputs should be provided.
NOTE The cable shielding must be connected to the functional earthing
1
(usually the
electrically conducting mounting plate) in order to prevent EMC interference in the
device.
In order to achieve this, for PROFIBUS DP connections it is mandatory that the metallic
metric EMC screws are used for the connection of the PROFIBUS DP shielding lead to the
frequency inverter or the housing of the technology unit. This ensures a wide area
connection of the functional earthing.
1
In systems, electrical equipment is usually connected to a functional earth. This serves as a means to dissipate leakage
and interference currents in order to ensure EMC characteristics and must therefore be implemented according to high
frequency technology aspects.