Mitsubishi FR-E 500 Instruction Manual page 51

" " " " 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
0dB=1µV
120dB=1V
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
inverter input side.
Inverter
power supply
Install filter FR-BIF to
inverter input side.
Separate inverter and power line 30cm
(11.81inches) or more (at least 10cm
(3.94inches)) from sensor circuit.
Control power
supply
Do not ground control
box directly.
Do not ground control cable.
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 (11.81 inches) 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 terminal Noise induced to signal cables by inverter output
cables
100
10
inverter to the power supply.
to
Control box Reduce carrier frequency.
FR-
Inverter
BSF01
FR-
BIF
Power supply
for sensor
38
INSTALLATION AND WIRING
Parallel cable
80
Twisted pair cable
60
40
Coaxial cable
20
FR-BSF01
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 cable.
Use twisted pair shielded cable.
Do not ground shield but connect it to signal
common cable.
Conditions
Inverter: FR-E520-3.7K-NA
Motor: FR-JR 4P 3.7kW (5HP)
Output frequency: 30Hz
Noise form: Normal mode
5cm
Inverter d(cm) Motor
FR-BLF
Terminal
(4T)
Measuring instrument
FR-BLF
to
FR-BSF01
Motor
IM
Sensor