NORD Drivesystems BU0200 - Manual (Page 38)

2 Assembly and installation
BU 0200 GB-4411 Subject to technical alterations 37
2.5 Wiring guidelines
The frequency inverter has been developed for use in an industrial environment. In this environment, high
levels of electromagnetic interference can influence the frequency inverter. 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 equipment in the control cabinet or field is securely earthed using short earthing cables
which have large cross-sections and are connected to a common earthing point or earthing rail. It is
especially important that all control devices connected to the frequency inverters (e.g. an automation
device) are connected to the same earthing point as the inverter itself, using a short cable with large
cross-section. Flat conductors (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 frequency inverter should be connected directly to the
earthing terminal of the associated frequency inverter. 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. (See also Section 9.3 / 9.4 (EMC))
(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 analog setpoint cables should only be earthed on one side on the frequency inverter.
(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 and brake chokes in the cabinet are interference protected, either by RC
circuits in the case of AC contactors, or by “free-wheeling” diodes for DC contactors, whereby the
interference protectors must be positioned on the contactor coils. Varistors for over-voltage
limitation are also effective. This interference suppression is particularly important when the contactors
are controlled by the relay in the frequency inverter.
(6) Use screened or armoured cable for the load connections (motor cable) and earth the
screening/armour at both ends, if possible to the frequency inverter bonding.
In addition, an EMC-compliant cabling must be ensured. (See also Section 9.3 / 9.4 (EMC)).
The safety regulations must be complied with under all circumstances when
installing the frequency inverter!
NOTE
The control cables, line cables and motor cables must be laid separately. In no circumstances
should they be laid in the same protective pipes/installation ducts.
The test for high voltage insulations must not be used on cables which are connected to the
frequency inverter.
ATTENTION
With the use of a ParameterBox SK PAR-3H this must never be simultaneously connected to
the frequency inverter and the PC, as potential shifts may cause damage, especially to the
PC. (See also Manual BU0040)