Mitsubishi Electric C70 Connection Manual page 111

MITSUBISHI CNC
Appendix 1. EMC Installation Guidelines
Example of surge absorber installation
An example of installing the surge absorber in the machine control panel is shown below.
A short-circuit fault will occur in the surge absorber if a surge exceeding the tolerance is applied. Thus,
install a circuit protection breaker in the stage before the surge absorber. Note that almost no current
flows to the surge absorber during normal use, so a breaker installed as the circuit protection for another
device can be used for the surge absorber.
Panel earth
leakage
Factory power
breaker
Input
power
Grounding
CAUTION
92
Transformer
Circuit
AC reactor
protector
A
Circuit
protector
B
Grounding plate
1. The wires from the surge absorber should be connected without extensions.
If the surge absorber cannot be installed just with the enclosed wires, keep the
2.
wiring length of A and B to 2m or less. If the wires are long, the surge absorber's
performance may drop and inhibit protection of the devices in the panel.
Surge absorber to be selected varies depending on input power voltage.
3.
Circuit
protector
NC unit
Other device
(panel power
supply, etc.)
Contactor
MC
Power supply
unit
and
drive unit
Other device
(panel power
supply, etc.)
(1) Surge absorber
(Protection across phases)
(2) Surge absorber
(Protection across each phase's grounding)
Control panel
(relay panel,
etc.)