Mitsubishi FR-A500 Series Instruction Manual page 46

• • • • Data line filter
Noise entry can be prevented by providing a data line filter for the detector cable etc.
• • • • Data examples
By decreasing the carrier frequency, noise will be about as low
as that of our conventional FR-Z200 series.
Noise Terminal Voltage of Inverter and Example
of Its Reduction by Noise Filters
120
100
80
60
20
0
0.1 0.3 0.5 1
Noise frequency (MHz)
*Noise terminal voltage: Represents the magnitude of noise propagated from the inverter to the power supply.
! Example of counter measures against noise
Install filter (FR-BLF,FR-
BSF01) to inverter input side.
Inverter power
supply
Separate inverter and power line
30cm (11.81 inches) or more
(at least 10cm (3.94 inches))
from sensor circuit.
Control power
supply
Do not ground control box directly.
Do not ground control cable.
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 in Pr. 240 will make it unoffending.
Differences between Noise Terminal Voltages
at Different Carrier Frequencies
120
FR-A520-3.7K
100
80
fc=0.7kHz
60
fc=2.0kHz Soft-PWM(Factory setting)
20
0
0.1 0.3 0.5 1
Noise frequency (MHz)
Conditions
" Motor:3.7kW (5HP)
" Average terminal voltage 0dB=1µV
120dB=1V
FR-Z220-3.7K
FR-A520-3.7K (fc=0.7kHz)
3 5 10
Control box
FR-
BLF
Install filter FR-BIF to
FR-
inverter input side.
BIF
Power
supply for
sensor
INSTALLATION AND WIRING
Conditions
" Motor: 3.7kW (5HP)
" Average terminal voltage 0dB=1µV
120dB=1V
FR-A220E-3.7k fc=(14.5kHz)
fc=14.5kHz
3 5 10
By using shielded cables as signal cables, induction noise can
be reduced greatly (to 1/10 - 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 1/2-1/3.)
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
Reduce carrier
frequency.
FR-
Inverter
BLF
Use twisted pair
shielded cable.
Do not ground shield but connect
it to signal common cable.
35
30
Conditions
" Inverter: FR-A520-3.7K
" Motor: FR-JR 4P 3.7kW (5HP)
" Output frequency: 30Hz
" Noise form: Normal mode
5cm
d(cm)
Inverter
FR-BLF
FR-BSF01
(4T)
Measuring instrument
Line-to-line distance, d (cm)
30 40 50
Install filter (FR-BLF,FR-BSF01)
to inverter output side.
Motor
Use 4-core cable for motor
power cable and use one
cable as ground cable.
Sensor
Motor
Terminal