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EMS measures to reduce electromagnetic noises that enter the inverter
or the converter unit 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 or the converter and it may malfunction due to electromagnetic noises, the
following measures must be taken:
• Provide surge suppressors for devices that generate many electromagnetic noises to suppress electromagnetic noises.
• Install data line filters
(page
• 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 or the converter unit to cause the peripheral devices to
malfunction
Noises generated from the inverter or the converter unit are largely classified into those radiated by the cables connected to
the inverter or the converter unit and its main circuits (I/O), those electromagnetically and electrostatically induced to the signal
cables of the peripheral devices close to the main circuit power supply, and those transmitted through the power supply cables.
Inverter or
Air propagated
converter
noise
unit generated
electromagnetic
noise
Electromagnetic
induction noise
Electrostatic
induction noise
Electrical path
propagated noise
Noise propagation
path
When devices that handle low-level signals and are liable to malfunction due to electromagnetic noises, e.g.
instruments, receivers and sensors, are contained in the enclosure that contains the inverter or the converter unit, or
when their signal cables are run near the inverter or the converter unit, the devices may malfunction due to by air-
propagated electromagnetic noises. The following countermeasures must be taken:
• Install easily affected devices as far away as possible from the inverter or the converter unit.
• Run easily affected signal cables as far away as possible from the inverter or the converter unit, and its I/O cables.
(a), (b), (c)
• Do not run the signal cables and power cables (inverter or converter unit I/O cables) in parallel with each other, and
do not bundle them.
• Set the EMC filter ON/OFF connector of the converter unit to the ON position. (Refer to
• Inserting a line noise filter into the output suppresses the radiated noise from the cables.
• Use shielded cables as signal cables and power cables and run them in individual metal conduits to produce further
effects.
When the signal cables are run in parallel with or bundled with the power cables, magnetic and static induction noises
may be propagated to the signal cables to cause malfunction of the devices and the following countermeasures must
be taken:
• Install easily affected devices as far away as possible from the inverter or the converter unit.
(d), (e), (f)
• Run easily affected signal cables as far away as possible from the inverter or the converter unit, and its I/O cables.
• Do not run the signal cables and power cables (inverter or converter unit I/O cables) in parallel with each other, and
do not bundle them.
• Use shielded cables as signal cables and power cables and run them in individual metal conduits to produce further
effects.
When the peripheral devices use the power system of the inverter or the converter unit, its generated noises may flow
back through the power supply cables to cause malfunction of the devices and the following countermeasures must
(g)
be taken:
• Set the EMC filter ON/OFF connector of the converter unit to the ON position. (Refer to
• Install the line noise filter to the power cables (output cables) of the inverter.
62) to signal cables.
Noise directly
radiated from inverter
Path (a)
or converter unit
Noise radiated from
Path (b)
power supply cable
Noise radiated from
Path (c)
motor connection cable
Path (d), (e)
Path (f)
Noise propagated
Path (g)
through power supply
cable
Noise from earthing
Path (h)
(grounding) cable due
to leakage current
(g)
(b)
(a)
(c)
Instrument
Receiver
Motor
Countermeasure
3. PRECAUTIONS FOR USE OF THE CONVERTER UNIT
3.1 Electro-magnetic interference (EMI) and leakage currents
(e)
Telephone
(g)
Converter
Sensor
power supply
unit
Inverter
(h)
(a)
(f)
(d)
(c)
Sensor
M
page
62.)
page
62.)
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