
B–63443EN/02
3. INSTALLATION
HARDWARE
11
The CNC unit has been steadily reduced in size using surface–mount and
custom LSI technologies for electronic components. The CNC unit also
is designed to be protected from external noise. However, it is difficult
to measure the level and frequency of noise quantitatively, and noise has
many uncertain factors. It is important to prevent both noise from being
generated and generated noise from being introduced into the CNC unit.
This precaution improves the stability of the CNC unit machine tool
system.
The CNC unit component units are often installed close to the parts
generating noise in the power magnetics cabinet. Possible noise sources
into the CNC unit are capacitive coupling, electromagnetic induction, and
ground loops.
When designing the power magnetics cabinet, guard against noise in the
machine as described in the following section.
The cables used for the machine are classified as listed in the following table:
Process the cables in each group as described in the action column.
Group Signal line Action
Primary AC power line Bind the cables in group A separate-
Secondary AC power line
ly (Note 1) from groups B and C, or
cover group A with an electromag-
A
AC/DC power lines
(containing the power lines for the servo motors and spindle motors)
cover group A with an electromag-
netic shield (Note 2).
See Section 3.5.4 and connect
AC/DC solenoid
See Section 3.5.4 and connect
spark killers or diodes with the sole-
AC/DC relay
noid and relay.
DC solenoid (24VDC) Connect diodes with DC solenoid
and relay.
DC relay (24VDC)
and relay.
Bind the cables in group B separate-
B
DC power line
ly from group A, or cover group B
with an electromagnetic shield.
DI/DO cable between the built–in I/O and power magnetics cabinet
Separate group B as far from Group
C as possible.
DI/DO cable between the built–in I/O and machine
It is more desirable to cover group B
with the shield.
Cable between the Power Mate and servo amplifier Bind the cables in group C sepa-
Cable for position and velocity feedback
rately from group A, or cover group
C with an electromagnetic shield.
Cable between the Power Mate and spindle amplifier
C with an electromagnetic shield.
Separate group C as far from Group
Cable for position coder
Separate group C as far from Group
B as possible.
C Cable for manual pulse generator
Be sure to perform shield proces-
Cable between the Power Mate and the CRT/MDI
sing in Subsec. 3.5.5.
RS–232–C interface cable
Battery cable
Other cables to be covered with the shield
3.5
ACTION AGAINST
NOISE
3.5.1
Separating Signal
Lines