Mitsubishi Electric FATEC FR-A800 Manual page 134

7
REVIEW OF INSTALLATION ENVIRONMENT
(4) Wiring distance of I/O cables
Restrictions differ depending on the I/O terminal. Although the control signals are isolated at the
input by photocoupler to improve noise tolerance, they are not isolated for the analog input.
Therefore, pay particular attention to the wiring of the frequency setting signal and shorten the
wire length as much as possible or take other countermeasures against the external noise. A
guide of the permissible wiring length for each signal and how to handle the length exceeding it
are shown in Fig. 7.40.
Power supply
cables of input side
When a voltage drops,
the maximum output
voltage of the inverter
does not exceed this
voltage.
MCCB
Power
supply
Contact input signal
When the distance is
long, set a relay near
the inverter.
Frequency
setting
potentiometer
Analog input signal
For the remote operation,
install the remote speed
setter near the inverter or
use 4 to 20 mA signal.
MC
R
S
T
Start
STF (STR), etc.
SD
30 m or less
Shielded cable
10
2
5
30 m or less
Fig. 7.40 Wiring lengths of I/O cables
7.3 Problems and measures when using inverter
Motor cables on the output side
Select the cable gauge to ensure
that the voltage drop is not large.
(Note that the output voltage is
low during output of a low frequency
depending on V/F pattern.)
Wiring must be within the overall
length described in Instruction
Manual in consideration of a charging
current caused by the stray
capacitances of the cable.
U
V
Inverter
W
RES
SD
30 m or less
Twisted cable or shielded cable
FM
SD
AM
5
30 m or less
200 m or less
1
2
3
Motor
4
IM
5
Reset
Frequency meter
6
(Digital)
7
8
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