
3. ACTION AGAINST NOISE
B--65245EN/02
TROUBLESHOOTING AND
COUNTERMEASURES
146
The following ground systems are provided for the CNC machine tool:
D The signal ground supplies the reference voltage (0V) of the electrical
signal system.
D The frame ground system is used for safety, and suppressing external
and internal noises. In the frame ground system, the frames, cases of
the units, panels, and shields for the interface cables between the units
are connected.
D The protective earth (PE) is designed so that the protective grounds
provided between the units are connected to ground at one point from
a system point of view.
D The grounding resistance of the protective earth shall be 100 ohms or
less (class D grounding).
D The protective earth (PE) cable must have enough cross --sectional area
to safety carry the accidental current flow into the protective earth (PE)
when an accident such as a short circuit occurs.
(Generally , it must have the cross--sectional area of the AC power cable
or more.)
D Use the cable contai ning the AC power wire and the protective earth
(PE) wire so that power is supplied with the ground wire connect ed.
D Ground
Notes on connecti n g the
ground systems