Power Supply Circuit Design - Mitsubishi Electric MELSEC Q Series User Manual

3 DESIGN

3.2.1 Power supply circuit design

This section describes the protective coordination and noise suppression techniques
of the power supply circuit.
(1) Separation and protective coordination (leakage current protection,
over current protection) of power supply lines
Separate the lines for PLC system power supplies from the lines for I/O devices
and servo amplifiers as shown below.
When there is much noise, connect an insulation transformer.
Main power
supply
100/200VAC
NFB
200VAC
(2) Grounding
The PLC system may malfunction as it is affected by various noises such as
electric path noises from the power supply systems, radiated and induced noises
from other equipment, servo amplifiers and their cables, and electromagnetic
noises from conductors. To avoid such troubles, connect the earthing ground of
each equipment and the shield grounds of the shielded cables to the earth.
For grounding, use the exclusive ground terminal wire of each equipment or a
single-point earth method to avoid grounding by common wiring, where possible,
since noises may sneak from other equipment due to common impedances.
Line noise filter
100/200VAC
Isolation
PLC power
transformer
supply
CP
I/O power
T1
supply
CP
Motor power supply
CP
Main circuit power supply
for servo amplifier
NFB
Control power supply
for servo amplifier
CP
PLC system
SSCNET
Servo amplifier
3 - 6
MELSEC-Q
PLC
system
I/O equipment
Motor equipment
Servo amplifier
Servo-
motor