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ANTRIEBSTECHNIK
17
;
A system should be broadly separated into power section and control section,
whether comprising a single enclosure or multiple enclosures. It is
recommended that a screen wall is installed between the two sections
because of the radiated noise from the power section. This screen must be
in good metal-to-metal contact with the mouting plate, over as large an area
as possible.
;
The inverter together with its filter must be mounted on a common mounting
plate. They must make good metal-to-metal contact with the mounting plate,
over as large an area as possible.
;
The connection cable between interference suppression filter and the inverter,
must be installed on both sides as a shielded cable normally no longer than
50 cm.
;
The mounting plate of the inverter must be seen as the neutral point for the
entire earthing and shield connection in the machine or system. If the motor
or other system parts lead to disturbances, then the HF-connection of these
elements is bad. In this case equipotential bonding must be done.
;
A good connection of the shield onto the motor terminal box is only given, when
the terminal box is made out of metal, and a metal cable gland is used to
connect the screen. When a plastic box is available, then the shield must be
equipped with a cable lug and be directly connected with the earthing point.
;
The leakage currents in the circuit increase when interference suppression
filters are used. Since these lie above the 3,5mA threshold, one of the
following conditions must be met:
– Protective conductor section at least 10 mm² copper
– Monitoring of the protective conductor by a device that independently
switches off under fault conditions.
– Install a second conductor electrically parallel to the protective conductor
via separate terminals.
;
If an additional line reactor is used because of the load on the mains, then this
must be installed on the mains side of the interference suppression filter.
3.4 Explanations
3.5 Connection of the Interference
Suppression Filter
The drawing below shows the assembly and connection of an external interference
suppression filter.
filtered cable to the frequency
inverter
Mount the filter directly to
the mounting plate in good
metal-to-metal contact
Equipotential bonding
Mains cable
Shielding bus out of copper, extensively
connect with the mounting plate
Additional earthing strip
Mounting plate
Protective conductor connected