Mitsubishi Electric 800 Series Hardware Instruction Manual page 80

 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 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 generated
Air propagated
electromagnetic
noise
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, 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 power supplies of the peripheral devices are connected to the power supply of the inverter or the converter
unit in the same line, its generated noises may flow back through the power supply cables to cause malfunction of
(g) 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
• Install the line noise filter to the power cables (output cables) of the inverter.
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
(h)
device to malfunction. In that case, disconnecting the earthing (grounding) cable from the device may stop the
malfunction of the device.
 Data line filter
Data line filter is effective as an EMI countermeasure. Provide a data line filter for the detector cable, etc.
• Commercially available data line filter: ZCAT3035-1330 (by TDK), ESD-SR-250 (by NEC TOKIN)
Noise directly radiated
Path (a)
from the inverter or the
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 through
Path (g)
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 INVERTER
3.1 Electro-magnetic interference (EMI) and leakage currents
(e)
Telephone
(g)
Converter
Sensor
power supply
unit
Inverter
(a)
(f)
(d)
(c) Sensor
M
page 81.)
page 81.)
1
2
3
4
5
(h)
6
7
8
9
10
79