NORDAC LINK (SK 155E-FDS / SK 175E-FDS) – Users Manual for Motor Starters as Field Distributors
38 BU 0155 en-3520
2.3 Electrical Connection
Electric shock
Dangerous voltages may be present at the plug contacts for the power connections (e.g. mains cable,
motor cable) even when the device is not in operation.
• Before starting work, check that all relevant components (voltage source, connection cables) are
free of voltage using suitable measuring equipment.
• Use insulated tools (e.g. screwdrivers).
• DEVICES MUST BE EARTHED.
Temperature sensor and PTC (TF)
As with other signal cables, thermistor cables must be laid separately from the motor cables
Otherwise the interfering signals from the motor winding that are induced into the line aff
device.
Ensure that the device and the motor are specified for the correct supply voltage.
Electrical connections are made exclusively with plug connectors.
2.3.1 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.
In addition, EMC-compliant wiring must be ensured.
The safety regulations must be complied with under all circumstances when installing the
devices!
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