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6. SUPPLEMENT
6.2 Reasons why the grounding position in the cabinet is specified to be 10 cm or less from the cabinet exit
Various devices are installed inside the cabinet. The devices radiate or transmit significant unnecessary noise.
The generated noise may not be held inside the cabinet depending on a cable wiring method.
When unnecessary noise is superimposed in the cable, grounding the cable near the cabinet exit should
prevent the noise from flowing outside the cabinet. Thus, grounding within 10 cm from the cabinet exit is
recommended.
6.3 Reasons why the shield must be grounded with the P clip or U clip
The surface of a shielded cable is covered with metallic foil or braid (braided wire). High-frequency noise is
passed through the shield and unnecessary noise is released outside to the ground, lowering the radiated
emissions level.
As to grounding the shielded cable, grounding with the P clip or U clip lowers impedance to the ground and
allows noise current to flow more smoothly than soldering the wire to the shield or holding the shield cables and
extending the length. Thus, grounding with the P clip or U clip is recommended.
Noise
To servo
amplifier
Fig. 6.5 Grounding within 10 cm from the cabinet exit
POINT
If removing the insulator of a shield causes electrical shock or injuries and
threatens the machinery safety, additional protective covers or enclosures may
be required.
Example of grounding
with the P clip
Fig. 6.6 Example of grounding the shielded cable
Cabinet
Device
10 cm or less
Shielded cable
Example of grounding
with the U clip
6 - 3
solder
Example of grounding
with wire soldering
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