NORDAC PRO (SK 500P) – Users Manual for Frequency Inverters
38 BU 0600 en-2319
2.5.2 Wiring guidelines
The soft starters 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 stirrups) 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.
The shields of analogue setpoint cables should only be earthed on one side on the device.
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.
This interference suppression is particularly important if the circuit breakers are controlled by the
relay in the frequency inverter.
6. Shielded or armoured cables should be used for the load connections (motor cable). The shielding
or armouring must be earthed at both ends. If possible, earthing should be made directly to the
electrically conducting mounting plate of the control cabinet or the screening angle of the EMC Kit.
In addition, EMC-compliant wiring must be ensured.
The safety regulations must be complied with under all circumstances when installing the
devices!
NOTICE!
Damage due to high voltage
The device may be damaged by electrical loads which do not correspond to its specification.
• Do not perform any high voltage tests on the device itself.
• Disconnect the cable which is to be tested from the device before perfor
insulation test.
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