
6.INSTALLATION CONDITIONS AND NOTES SVM B-65322EN/02
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6.3.2 Grounding
A CNC machine tool has three separate ground systems:
(1) Signal ground (SG) system
The signal ground (SG) system provides the reference potential
(0V) for the electrical signal system.
(2) Frame ground (FG) system
The frame ground (FG) system is provided to ensure safety and
to shield external and internal noise. For example, the equipment
frames, unit cases, panels, and interface cables connecting
devices are all shielded.
(3) System ground system
The system ground system is designed to connect each unit and
the inter-unit frame ground system to ground.
Power
magnetics
unit
Servo
amplifier
CNC
Operator’s panel
Main unit
Distribution board
Power magnetics unit
Signal Ground system
Flame Ground system
System Ground system
WARNING
[Warning on ground system wiring]
1 The ground resistance of the system ground must
not exceed 100 Ω (class-3 ground).
2 System ground connection cables must have a
sufficiently large cross-sectional area to enable
them to safely carry the current that will arise in the
event of a mishap such as a short-circuit. (In
general, a cross-sectional area no less than that of
the AC power line must be provided.)
3 The system ground connection cable shall be
integrated with the AC power line, such that power
cannot be supplied if the ground wire is
disconnected.