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Main circuit terminals
1.2.8 Regarding noise and the installation of a noise filter
Some noise enters the inverter causing it to malfunction and others are generated by
the inverter causing the malfunction of peripheral devices. Though the inverter is
designed to be insusceptible to noise, it handles low-level signals, so it requires the
following general countermeasures to be taken.
(1) General countermeasures
• Do not run the power cables (I/O cables) and signal cables of the inverter in parallel
with each other and do not bundle them.
• Use twisted shield cables for the detector connecting and control signal cables and
connect the sheathes of the shield cables to terminal SD.
• Ground the inverter, motor, etc. at one point.
• Capacitances exist between the inverter's I/O wiring, other cables, ground and
motor, through which leakage currents flow to cause the earth leakage circuit
breaker, ground leakage relay and external thermal relay to operate unnecessarily.
To prevent this, take appropriate measures, e.g. set the carrier frequency in Pr. 72 to
a low value, use a ground leakage circuit breaker designed for suppression of
harmonics and surges, and use the electronic thermal relay function built in the
inverter.
• The input and output of the inverter main circuit include high-degree harmonics,
which may disturb communication devices (AM radios) and sensors used near the
inverter. In this case, install a FR-BIF(-H) optional radio noise filter (for use on the
input side only) or FR-BSF01 line noise filter to minimize interference.
<Noise reduction examples>
Power
supply
for sensor
Inverter
power supply
Control
power supply
Control
box
Reduce carrier
frequency.
IM
FR-
BSF01
FR-BSF01
Sensor
Use twisted pair shielded cable.
Moto
r
Install filter
on inverter's output side.
Inverter
FR-BIF
Install filter FR-BIF
on inverter's input side.
FR-
BSF01
FR-BSF01
Install filter
on inverter's input side.
Separate inverter and power line
by more than 30cm (3.94inches)
and at least 10cm (11.81inches)
from sensor circuit.
Do not ground control
box directly.
Do not ground
control cable.
Use 4-core cable for motor
power cable and use one
cable as ground cable.
Do not ground shield but connect
it to signal common cable.