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Table 3-4 Table for noise suppression measures
Noise transmission path Measure for reducing influence
②
If the external devices form a closed loop through the drive wiring, the drive grounding cable
will have leakage current, which will cause the relevant device to mis-operate. The
mis-operation can be reduced by removing the grounding.
③
When the external devices and drive share the same power system, the noise generated by
the drive will transmit along the power cable in a reverse direction, causing all the other
devices in the same system to mis-operate. The following measures can be taken to prevent it:
installing the noise filter at the input end of the drive, isolating the noise for other devices with
the isolation transformer or power filter.
④⑤⑥
If the devices for processing the weak signals of the measuring instruments, radio devices and
sensors and their signal cables are installed in the same cabinet with the drive, and the wirings
are close to each other, mis-operation may be caused due to the space noise influence. To
deal with this problem, the following measures shall be taken:
(1) The equipment and signal cables vulnerable to influence shall be kept far away from the
drive. The signal cable shall adopt shielded wire, with the shielded layer grounded. Besides,
the shielded cable shall be sleeved with metal tube and kept far away from the drive and its
input/output wire. If the signal cable must pass the power cable, they shall adopt orthogonal
layout.
(2) Install the radio noise filter and linear noise filter (ferrite common mode choke) at the input
and output ends of the drive to suppress the radiation noise of the power cable.
(3) The motor cable shall be placed in the thick shelter, such as the pipe with large thickness
(more than 2mm), or bured into the cement trough. The power cable shall be sleeved with
metal pipe and grounded using shielded cable (the motor cable shall adopt 4-core cable, with
one piece grounded at the drive side, and the other end connected to the motor enclosure)
①⑦⑧
If the signal cables are laid in parallel with the power cables or bundled together with the
power cables, because of electromagnetic induction noise and static induction noise, the noise
will transmit in the noise cable, causing mis-operation of the relevant equipment. Such wiring
mode shall be avoided, the vulnerable equipment shall be kept far away from the drive, and
vulnerable signal cables shall be kept far away from the drive input/output cable. The signal
cable and power cable shall adopt shielded cable and be sleeved with metal tube respectively.
The distance between the metal tubes shall be at least 20cm.
3.3.2 Field wiring requirements
To avoid the interference coupling, the control cable, power cable and motor cable shall be separately
installed and kept away from each other, especially when the cables are parallel and extend for a long
distance. If the signal cable must cross the power cable, make the crossing perpendicular.
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