Chapter 9 Options
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Ch
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ter 9
below).For input cables can use four-core cable, but still recommended to use shielded symmetrical
cable. Compared to a four-core cable, shielded symmetrical cables can not only reduce the loss and
cost of the current flowing through the motor cable, but also can reduce the electromagnetic radiation.
PE conductor
shield
conductor
Jacket
Insulation
shield
PE
Symmetrical shielded motor cables
Four-core cable
PE
conductor
conductor
Jacket
Jacket
Insulation
Insulation
Note: If conductivity of the cable shield can not meet the requirements, you must use a separate
PE conductor.
To play a protective role of conductor, when the shield wire and phase conductors using the same
material, the cross-sectional area of the shield wire and phase conductors cross-sectional area must be
the same, aims to reduce grounding resistance, impedance continuity better.
To effectively suppress RFI transmission and conduction, the shield conductivity must be at least
1/10 of the phase conductor conductivity. For copper or aluminum shield, this requirement is very
easy to meet. Minimum requirements for the drive motor cable as shown below. Cable comprising a
layer of copper spiral. Shield tight as possible, that the more tightly the more we can effectively
suppress radiated electromagnetic interference.
Insulating layer
Shield
Cable cross section
2. Control Cable
All analog control cables and cables for the frequency input must be shielded. Analog signal
cable double-shielded twisted pair cable as shown in Figure 1. Each signal uses one pair individually
shielded twisted pair cable pair. Do not use the different analog signal with a ground wire.
Plurality of double-shielded twisted pair cable
plurality of single-shielded twisted pair cable
Diagram
1
Diagram
2
For low-voltage digital signals, double-shielded cable is the best choice, but can also be a single-
shielded or unshielded twisted pair, as shown in Figure 2, however, the frequency of the signal, it can
only use a shielded cable.
Relay cable need to use cables with metal braid shield.
Need to use a network cable to connect the keyboard, for electromagnetic environment is more
complex place, it is recommended to use shielded cable.
Note: analog and digital signals using different cables routed separately.
9-8-4 Interference countermeasures
