NORDAC ON / ON+ (SK 3xxP) – Manual with installation instructions
32 BU 0800 en-4521
2.6.4 Wiring guidelines
The devices have been developed for use in an industrial environment. In this environment,
electromagnetic interference can affect the device. In general, correct installation ensures safe and
problem-free operation. To meet the limiting values of the EMC directives, the following instructions
should be complied with.
1. Ensure that all devices are securely earthed to a common earthing point or earthing rail using short
earthing cables with a large cross-section. It is especially important that each control unit which is
connected to the electronic drive technology (e.g. an automatic device) has a short cable with a
large cross-section, which is connected to the same earthing point as the device itself. Flat cables
(e.g. metal clamps) are preferable, as they have a lower impedance at high frequencies.
2. The bonding cable of the motor controlled by the soft starter should be connected directly to the
earthing terminal of the associated device. The presence of a central earthing bar in the control
cabinet and the grouping together of all bonding conductors to this bar normally ensures safe
operation.
3. Where possible, shielded cables should be used for control circuits. The shielding at the cable end
should be carefully sealed and it must be ensured that the wires are not laid over longer distances
without shielding.
4. The control cables should be installed as far as possible from power cables, using separate cable
ducts, etc. Where cables cross, an angle of 90° should be ensured as far as possible.
5. Ensure that the contactors in the cabinet are interference protected, either by RC circuits in the
case of AC contactors or by free-wheeling diodes for DC contactors, for which the interference
traps must be positioned on the contactor coils. Varistors for over-voltage limitation are also
effective.
6. Shielded or armoured cables should be used for the load connections (motor cable). The shielding
or armouring must be earthed at both ends. The shielding or armouring must be connected over a
large area on the plug connector housing.
Furthermore, attention must be paid to the EMC-compliant wiring.
During the installation of the devices, the safety requirements must not be violated under any
circumstances!
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