![background image](http://html1.mh-extra.com/html/omron/sysmac-c500-nc222-e/sysmac-c500-nc222-e_operation-manual_742438037.webp)
26
2-5
Wiring Precautions
Electronically controlled equipment may malfunction because of noise gener-
ated by power supply lines or external loads. Such malfunctions are difficult
to reproduce; hence, determining the cause often requires a great deal of
time.
The Position Control Unit is naturally susceptible to noise malfunction. The
following tips, however, should aid in avoiding noise malfunction and improve
system reliability.
1.
Always use designated electrical cables.
2.
Separate power cables (AC power supply, motor power supply) and
control cables (pulse outputs, external I/O). Do not group the two types
together or place them in the same conduit.
3.
Control cables must be shielded.
4.
For inductive loads (relays, solenoids, solenoid valves), connect surge
absorbing circuits. Connect surge absorbing components close to the
relay or solenoid. For a DC relay, use a surge-absorbing diode with a
voltage tolerance at least five times greater than the circuit voltage.
–
+
DC
RY
Solenoid
SOL
Surge absorber
Surge absorber
RY
AC
DC Relay
AC Relay
Diode for
absorbing surge
5.
Noise from the power supply line (e.g., when using the same power sup-
ply with an electric welder or electrical discharge unit, or when a
high-frequency noise generator is nearby) can be alleviated by inserting
a noise filter at the power supply input.
6.
Use twisted pair cable for power supply lines.
7.
Use adequate grounds with a cross-section of 1.25 mm
2
or greater.
Ground at a resistance no greater than 100
Ω
.
8.
The I/O terminals that operate the 24-V system are isolated with photo-
couplers to reduce external noise effects on the control system. In ac-
cordance with this provision, avoid connections between the analog con-
trol voltage ground (AG) and 24-V ground (DC GND).
1, 2, 3...
Wiring Precautions
Section 2-5