Mitsubishi Electric FR-CC2-P, Instruction Manual

Page: 64 / 184

Electro-magnetic interference (EMI) and leakage currents
PRECAUTIONS FOR USE OF THE CONVERTER UNIT
63
3
• Techniques to reduce electromagnetic noises that are radiated by the inverter or the converter unit to cause the peripheral
devices to malfunction (EMI countermeasures)
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 their main circuits (I/O), those electromagnetically and electrostatically induced to the
signal cables of the peripheral devices close to the main circuit cables, and those transmitted through the power supply
cables.
Noise
propagation
path
Countermeasure
(a) (b) (c)
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 their I/O
cables.
• Do not run the signal cables and power cables (I/O cables of the inverter or the converter unit) 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 page 65 .)
• 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.
(d) (e) (f)
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.
• Run easily affected signal cables as far away as possible from the I/O cables of the inverter or the converter unit.
• Do not run the signal cables and power cables (I/O cables of the inverter or the converter unit) 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.
(g)
When the peripheral devices use the power system of the inverter or the converter unit, noises generated from the
inverter or the converter unit may flow back through the power supply cables to cause malfunction of the devices and
the following countermeasures must be taken:
• Set the EMC filter ON/OFF connector of the converter unit to the ON position. (Refer to
page 65 .)
• Install the line noise filter to the power cables (output cables) of the inverter.
(h)
When a closed loop circuit is formed by connecting the peripheral device wiring to the inverter or the converter unit,
leakage currents may flow through the earthing (grounding) cable of the inverter or the converter unit to cause the
device to malfunction. In that case, disconnecting the earthing (grounding) cable from the device may stop the
malfunction of the device.
Noise propagated
through power supply
cable
Path (c)
Path (b)
Path (a)
Noise directly
radiated from inverter
or converter unit
Path (d), (e)
Air propagated
noise
Path (f)
Electrical path
propagated noise
Path (h)
Path (g)
Inverter or
converter
unit generated
electromagnetic
noise
Electromagnetic
induction noise
Electrostatic
induction noise
Noise radiated from
power supply cable
Noise radiated from
motor connection cable
Noise from earthing
(grounding) cable due
to leakage current
M
(a)
(b)
(c)
(c)
(h)
(g)
(e)
(g)
(d)
(f)
(a)
Instrument Receiver
Sensor
power supply
Motor
Telephone
Sensor
Converter
unit
Inverter