Mitsubishi Electric FR-E520 Instruction Manual page 55

! ! ! ! Data line filter
Noise entry can be prevented by providing a data line filter for the detector or other
cable.
! ! ! ! Data examples
By decreasing the carrier frequency, the
noise terminal voltage* can be reduced.
Use Pr. 72 to set the carrier frequency to
a low value (1kHz).
Though motor noise increases at a low
carrier frequency, selection of Soft-PWM
will make it unoffending.
Differences between
voltages at different carrier frequencies
Conditions
Average terminal voltage
120
Carrier frequency 10kHz
100
80
60
40
Carrier frequency 1kHz
20
0
0.1 1
Noise frequency (MHz)
* Noise terminal voltage:Represents the magnitude of noise propagated from the
! ! ! ! Example of counter measures against noise
FR-BLF
Install filter
FR-BSF01
to inverter input side.
Inverter
power supply
Install filter FR-BIF to
inverter input side.
Separate inverter and power line
by more than 30cm and at least
10cm from sensor circuit.
Control power
supply
Do not earth (ground) control
box directly.
Do not earth (ground) control cable.
noise terminal
0dB=1µV
120dB=1V
10
inverter to the power supply.
Control box Reduce carrier frequency.
FR-
Inverter
BSF01
FR-
BIF
Power supply
for sensor
INSTALLATION AND WIRING
By using shielded cables as signal
cables, induction noise can be reduced
greatly (1/10 to 1/100). Induction noise
can also be reduced by moving the
signal cables away from the inverter
output cables.
(Separation of 30cm reduces noise to 1/
2 to 1/3.)
By fitting the FR-BSF01 or BLF on the
inverter output side, induction noise to
the signal cables can be reduced.
Noise induced to signal cables by
inverter output cables
100
Parallel cable
80
Twisted pair cable
60
40
Coaxial cable
20
0
10 20 30 40 50
Line-to-line distance d (cm)
Install filter
inverter output side.
FR-
BSF01
Use 4-core cable for motor power
cable and use one wire as
earth (ground) cable.
Use twisted pair shielded cable.
Sensor
Do not earth (ground) shield but connect it to
signal common cable.
45
Conditions
･ Inverter: FR-E520-3.7K
･ Motor: FR-JR 4P 3.7kW
･ Output frequency: 30Hz
･ Noise form: Normal mode
5cm
Inverter d(cm) Motor
FR-BLF
FR-BSF01
Terminal
(4T)
Measuring instrument
FR-BLF
to
FR-BSF01
Motor
IM
2