REFUdrive 500 RD51
Electrical installation
3-1
DOK-RD500*-RD51*******-IB01-EN-P
3
Electrical installation
3.1
EMC-compatible drive design
The following 10 rules are the basics for designing drive systems which
are EMC-compatible. You’ll find details in the Instruction Manuals sup-
plied with the equipment.
You can obtain a detailed description "EMC-compatible drive design“ from
Indramat Refu, or from the Internet under http://www.refu.com.
Rules 1 to 7 are generally valid. Rules 8 to 10 are especially important to
limit noise emission.
All metal parts of the cabinet should be connected with one another
through the longest possible surface so that the best electrical connection
is established. (Not paint on paint!) If required, use serrated washers
which cut through the paint surface. The cabinet door should be con-
nected to the cabinet using the shortest possible grounding straps.
Signal-, line supply-, motor- and power cables should be routed away
from another (this eliminates mutual interference!). The minimum clear-
ance is: 20 cm. Barriers should be provided between power- and signal
cables. These barriers should be grounded at several locations.
Contactors, relays, solenoid valves, electromechanical operating hours
counters etc. in the cabinet must be provided with noise suppression de-
vices, e.g. using RC elements, diodes, varistors. These devices must be
connected directly at the coil.
Unscreened cables of the same circuit (feeder and return cables) should
be twisted with the smallest possible distance between them. Cores which
are not used must be grounded at both ends.
Generally, noise which is coupled-in can be reduced by routing cables as
close as possible to grounded sheet steel panels. For this reason, cables
and wires should not be routed freely in the cabinet, but as close as pos-
sible to the cabinet itself and the mounting panels. This is also true for
reserve cables.
Incremental encoders must be connected using a shielded cable. The
shield must be connected at the incremental encoder and at the AC drive
converter through the largest possible surface area. The shield may not
be interrupted, e.g. using intermediate terminals.
The screens of signal cables must be connected to ground at both ends
through the largest possible surface area to establish a good electrical
connection (transmitter and receiver). If the potential bonding between the
screen connections is poor, to reduce the screen current, an additional
potential bonding conductor with a cross section of at least 10 mm²
should be connected in parallel with the screen. The screen can be con-
nected to ground (=cabinet housing) at several locations. This is also true
outside the cabinet. Foil screens are not recommended. Braided screens
provide a better screening (factor of 5). If the potential bonding is poor,
analog signal cables may only be connected at one end to the drive con-
verter in order to prevent low-frequency noise being injected into the
screen (50 Hz).
Always locate a radio interference suppression filter close to the noise
source. The filter should be connected through the largest possible sur-
face area with the cabinet housing, mounting panel etc. The best solution
is a bare metal mounting panel (e.g. manufactured from stainless steel,
galvanized steel), as the complete mounting surface can be used to es-
tablish good electrical contact.
The incoming and outgoing cables of the radio interference suppression
filter should be separated.
Rule 1
Rule 2
Rule 3
Rule 4
Rule 5
Rule 6
Rule 7
Rule 8
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