Mitsubishi Electric FR-A700 Technical Manual page 529

4.2.2 Automatic operation using 4 to 20mADC current signal
MCCB
Power
supply
Frequency
meter
Hz
Remote installation
Current signal
for automatic
operation
4 to 20mADC
Start switch
Stop switch
DC
power
supply
*1 Separate the signal cable from the power cable. Not doing so can cause the signal line to act as an antenna and be affected
more easily by external noise.
*2 The frequency meter connection cable may be increased up to 200m in length. (Install the calibration resistor near the
frequency meter.)
*3 When the electric channel length between the inverter and motor is long:
1) As the output voltage of the inverter includes high frequency, continuous leakage current due to the to-ground
capacitances in the inverter-to-motor electric channel increases and the earth leakage circuit breaker or earth
leakage relay may operate unnecessarily.
Wire the cables between the inverter and motor over the shortest distance and increase the electric channel-to-
ground distance.
2) At a low frequency, the motor torque may decrease due to a voltage drop in the cables. (Refer to page 530)
*4 When an inverter with a regenerative brake resistor is used for cyclic or heavy duty operation, it is recommended to install a
magnetic contactor in the primary side to prevent discharging resistor from overheat/burnout if the regenerative brake transistor
is damaged due to the thermal capacity shortage of the discharging resistor, and excessive regenerative brake duty, etc.
*5 When running two inverters with a 4 to 20mADC current signal at the same time, connect terminals 4-5 in series. Note the
power supply capacity of the 4 to 20mADC signal.
Calibration
resistor
Twisted cable or twisted
shielded cable used
R
Frequency setting
potentiometer
C
X
T
X
Inverter
MC
*4
R U
S V
T W
FM
SD
CR1
STF(STR)
CR2
AU
SD
10
2
5
4
4
*5
5
CX
CR1
Manual operation
Automatic operation
563
PRACTICAL CIRCUITS
common
(common)
Motor
IM
Ground
200VAC
TX
C
R
1
C
R
2
4