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Mitsubishi Electric FR-F800 Series Instruction Manual page 94

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3.1.2
Some electromagnetic noises enter the inverter to cause the inverter malfunction, and others are radiated by the inverter to
cause the peripheral devices to malfunction. (The former is called EMS problem, the latter is called EMI problem, and both is
called EMC problem.) Though the inverter is designed to be immune to noises, it requires the following basic measures and
EMS measures as it handles low-level signals. Pay attention to the electromagnetic noises that could be generated by the
inverter since the inverter chops outputs at high carrier frequency. If these electromagnetic noises cause peripheral devices to
malfunction, EMI countermeasures should be taken to suppress noises. These techniques differ slightly depending on EMI
paths.
 Basic measures
• 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 shielded twisted pair cables for the detector connecting and control signal cables and connect the sheathes of the
shielded cables to terminal SD.
• Ground (Earth) the inverter, motor, etc. at one point.
 EMS measures to reduce electromagnetic noises that enter the inverter
and cause it to malfunction
When devices that generate many electromagnetic noises (which use magnetic contactors, electromagnetic brakes, many
relays, for example) are installed near the inverter and the inverter may malfunction due to electromagnetic noises, the
following countermeasures must be taken:
• Provide surge suppressors for devices that generate many electromagnetic noises to suppress electromagnetic noises.
• Install data line filters to signal cables (refer to
• Ground (Earth) the shields of the detector connection and control signal cables with cable clamp metal.
 EMI measures to reduce electromagnetic noises that are radiated by the
inverter to cause the peripheral devices to malfunction
Inverter-generated noises are largely classified into those radiated by the inverter itself and by the I/O cables connected to its
main circuit, those electromagnetically and electrostatically induced to the signal cables of the peripheral devices close to the
power cable connected to the inverter main circuit, and those transmitted through the power cables.
Inverter generated
electromagnetic
noise
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Techniques and measures for electromagnetic
compatibility (EMC)
Air propagated
Noise directly
radiated from inverter
noise
Noise radiated from
power supply cable
Noise radiated from
motor connection cable
Electromagnetic
Path (d), (e)
induction noise
Electrostatic
Path (f)
induction noise
Electrical path
Noise propagated through
power supply cable
propagated noise
Noise from earthing
(grounding) cable due to
leakage current
search engine
page
94).
Path (a)
Path (b)
Path (c)
(g)
Instrument
Path (g)
Path (h)
3. PRECAUTIONS FOR USE OF THE INVERTER
3.1 Electro-magnetic interference (EMI) and leakage currents
(e)
(g)
(b)
(a)
power supply
Inverter
(c)
Receiver
(a)
(f)
(d)
(c)
Motor
M
1
2
3
4
5
6
7
8
9
10
Telephone
Sensor
(f)
Sensor
93

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