INSTALLATION AND WIRING
34
••••
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 in Pr. 240 will
make it unoffending.
Differences between Noise Terminal Voltages
at Different Carrier Frequencies
0.1
0.3
0.5
1
3
5
10
30
20
60
80
100
120
0
FR-F520-3.7K
fc=0.7kHz
fc=14.5kHz
fc=2.0kHz Soft-PWM(Factory setting)
FR-A120E-3.7K fc=14.5kHz
Conditions
!
Motor: 3.7kW (5HP)
!
Average terminal voltage 0dB=1
µ
V
120dB=1V
No
ise
te
rmin
a
l v
o
lt
a
ge (
d
B
)
Noise frequency (MHz)
By decreasing the carrier frequency, noise will be
about as low as that of our conventional FR-Z200
series.
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 (11.81inches) 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 Terminal Voltage of Inverter and Example
of Its Reduction by Noise Filters
0.1
0.3
0.5
1
3
5
10
30
20
60
80
100
120
0
FR-F520-3.7K(fc=0.7kHz)
FR-Z220-3.7K
Noise frequency (MHz)
N
o
is
e ter
m
inal
v
o
lt
age (
d
B)
Conditions
!
Motor:3.7kW (5HP)
!
Average terminal voltage 0dB=1
µ
V
120dB=1V
Noise Induced to Signal Cables by Inverter Output
Cables
20
40
60
80
100
10
0
20
30
40
50
5cm
d(cm)
FR-BLF
FR-BSF01
(4T)
Line-to-line distance, d (cm)
Ind
u
c
ti
on
v
o
lt
age
(
d
B
)
Parallel cable
Twisted pair cable
Coaxial cable
Conditions
!
Inverter: FR-F520-3.7K
!
Motor: SF-JR 4P 3.7kW (5HP)
!
Output frequency: 30Hz
!
Noise form: Normal mode
Inverter
Motor
Terminal
Measuring instrument
*Noise terminal voltage: Represents the magnitude of noise propagated from the inverter to the power supply.
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