Protective Measures Against Lightning Surge - Mitsubishi Electric MELDAS 600 Series Connection Manual

3.3.4 Protective Measures against Lightning Surge

Generally, lightning surge infiltrates the control power supply from the power supply line. Then the
internal circuit is damaged by this control power supply, or via this control power supply.
The Mitsubishi NC unit has a surge absorber on the control power supply for the NC control section and
NC control section. However, this measure is not taken through the control panel, as shown in Fig. 1, so
the lightning surface could flow over the signal line and damage the other devices.
Power supply line
(1) Methods of 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 measures are required as protection against general damage.
1) Installation of surge absorber
2) Installation of circuit protector
Power supply line
Fig. 2 Lightning surge measures for single-phase power supply line
Power supply line
Circuit
protector
Fig. 3 Lightning surge measures for 3-phase power supply line
CHAPTER 3 INSTALLATION
3.3 Noise Countermeasures
Fig. 1 Path of damage caused by lightning surge
Circuit
protector
Surge absorber (1)
Surge absorber (2)
NC control
section
NC drive section
(Servo, spindle
amplifier)
Lightning surge path
Power supply
for panel
Other device
(power supply
for panel, etc.)
Other device
(power supply
for panel, etc.)
Surge absorber (3)
14
Control panel
(Relay panel,
etc.)
Control panel
(Relay panel,
etc.)
Control panel
(Relay panel,
etc.)