Goodrive270 series VFD for fan and pump Optional peripheral accessories
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Compared with four-core cables, symmetrical shielded cables can reduce electromagnetic radiation
as well as the current and loss of the motor cables.
Shield layer
Jacket
Insulator
Conductor
PE
PE conductor and
shield layer
Jacket
Insulator
Conductor
Jacket
Insulator
Conductor
PE
Symmetrical shielded cable
Four-core cable
Note: If the electrical conductivity of the motor cable shield layer does not meet the
requirements, a separate PE conductor must be used.
To protect the conductors, the cross-sectional area of the shielded cables must be the same as that of
the phase conductors if the cable and conductor are made of materials of the same type. This
reduces grounding resistance, and thus improves impedance continuity.
To effectively restrict the emission and conduction of radio frequency (RF) interference, the
conductivity of the shielded cable must at least be 1/10 of the conductivity of the phase conductor.
This requirement can be well met by a copper or aluminum shield layer. Figure D±1 shows the min.
requirement on motor cables of VFD. The cable must consist of a layer of spiral-shaped copper strips.
The denser the shield layer is, the more effectively the electromagnetic interference is restricted.
Insulating layer
Shield layer
Figure D±1 Cable cross section
D.4.2 Control cables
All analog control cables and cables used for frequency input must be shielded cables. Analog signal
cables need to be double-shielded twisted-pair cables (as shown in figure a). Use one separate
shielded twisted pair for each signal. Do not use the same ground wire for different analog signals.
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