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3. INSTALLATION
3.4 Noise Countermeasures
I - 15
3.4.4 Countermeasures against Lightning Surge Protection
Generally, lightning surge infiltrates the control power supply from the power supply line. This control
power supply or the internal circuit can be damaged by lightning surge via the control power supply.
If this countermeasure is not taken throughout the control panel as shown in Fig. 1, the lightning surge
could flow over the signal line and damage the other devices.
Power
supply line
NC control
section
Power supply
for panel
NC drive section
(Servo, spindle
amplifier)
Control panel
(Relay panel,
etc.)
Lightning surge path
Fig. 1 Path of damage caused by lightning surge
(1) Protective measures
Install the surge absorber on the power supply line for the separately prepared power supply units,
etc., as shown in Fig. 2 and Fig. 3.
The following two countermeasures are required as protection against general damage.
1) Installation of surge absorber
2) Installation of circuit protector
Control panel
(Relay panel,
etc.)
Other device
(Power supply
for panel,
etc.)
Surge absorber (1)
Circuit protector
Power
supply line
Fig. 2 Lightning surge countermeasures for single-phase power supply line
Control panel
(Relay panel,
etc.)
Other device
(Power supply
for panel,
etc.)
Surge absorber (2)
Circuit protector
Power
supply
line
Surge absorber (3)
Fig. 3 Lightning surge countermeasures for 3-phase power supply line