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CHAPTER 3 - Installation of the drive
3.3.8.1
The layout of the components inside the electric cabin, both in terms of location and in
terms of distances, must be carried out with the criterion to minimize the mutual
influences of the equipment assembled for electromagnetic disturbances.
As an example, keep in mind that some types of transformers, power impedances or even
coils of contactors can produce rather high fields at short distance.
3.3.8.2
Cablings of power circuits must be physically separated from the cablings of the
command and control circuits (signal circuits); power circuits must be accurately
shielded as against the signal circuits; this is obtained either by using metal raceways
or metal shields in the electric cabin or by using shielded cables, also power cables,
inside plastic raceways.
As an example, power circuits (cables that in Fig. 4-4 and 4-5 reach terminal boards N1A or
N1B) must be kept separate, as mentioned above, from the cables that reach terminal boards
J1 and J2.
3.3.8.3
All apparatus, for which accessories are prescribed to make them comply with EMC
standards, must be equipped with such accessories, assembled according to the
instructions of the manufacturer.
For example, the devices against disturbances to be assembled in parallel to ac contactor
coils, the diods to be assembled in parallel to the relays or contactors with dc coils, the filters
against HF conducted disturbances to be assembled on the line input of some convertors.
3.3.8.4
Cable shieldings must stop as nearer as possible the terminal board; if the connection
of the shield to a mass or, in some cases, to ground is prescribed, it must be carried
out with the shortest possible connections and with conductors with an adequate
section.
3.3.8.5
lt is important that all panels within the electric board are connected with mechanical
connections that present low electrical impedance at high frequencies.
As an example, to obtain this it may be necessary to add locking screws, to remove the paint
in the interconnecting parts, to use special metal shields for EMC.
3.3.9 Electric system
As already stated in paragraph 3.3.7, we refer to the system "in situ", in the final installation of
the machine. For some types of machines (as for example small machine tools) the electric
cabinet is physically connected to the machine, therefore, in practice, the electric system «in
situ" is reduced to the connection of the machine to the supply line.
Usually, however, the electric cabinet is situated at a certain distance from the machine, on
which the motor is assembled; sometimes there is also a remote control device, to which
conductors may be connected.
In this case, since the problem of emissions is tightly connected to system factors, the
following recommendations derive from technical competence and experience in field and
must be essentially regarded as guidelines and not as solutions.
3.3.9.1
Keep in mind that (paragraph 1.2.13) the BHL-D convertor is intended to be used in
"Second Environment", i.e., in practice, to the use in industrial environments, where
the low voltage net does not supply domestic buildings.
MANIU04.9607 GB 03/97
Page 3.11
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