Installation and Wiring
24
Loop
equipment. If the equipment is not earthed, there will be fewer misoperations.
Power Cable
Transmission
In cases where the peripherals and the inverter share the same power supply,
the interference generated by the inverter will be transmitted along the power
cable in a reversed direction and cause misoperations of other equipment in the
same system. The following steps may be taken:
(1)Install an EMI filter or a ferrite chip common-mode filter (magnetic core) at the
input end of the inverter.
(2) Use an isolation transformer or a power supply filter to isolate the noise of
other equipment.
Motor Radiation
Power Cord
Radiation
Inverter
Radiation
In cases where measurement instruments, radio devices, transducers and other
equipment or signal lines emitting feeble signals are housed in the same cabinet as
the inverter and the different wirings are closely arranged, there are more chances
of misoperations as a result of interference. The following solutions are
recommended:
(1) Devices and signal lines susceptible to interference must be installed at an
appropriate max distance from the inverter. The signal lines must be
shielded and the shielding layer must be earthed and the signal lines must be
housed in metal tubes. An appropriate max distance must be kept between
the signal lines and the inverter or its lead-in/lead-out wires. In cases where
a signal line has to cross over a power cable, they must be vertical to each
other.
(2) Install EMI filters or ferrite chip common-mode filter (magnetic core) on both
the input side and the output side of the inverter.
(3) The motor cable must be housed in an enclosure of relatively great thickness,
e.g. tubes of relatively great thickness (above 2mm), or buried in a cement tub.
The power cable must be earthed shielded cable housed in a metal tube (The motor
cables must adopt 4-core cables. One cable is earthed on the inverter side and the
other is connected to the motor enclosure).
Electrostatic
Induction
Electromagnetic
Induction
(1) Signal lines must not run parallel to or be bound along with power cables.
(2) Equipment or signal lines susceptible to interference must be at a max
appropriate distance from the inverter and its lead-in/out wires.
(3) Signal lines and power cables must be shielded lines housed in metal tubes.
Metal tubes must be spaced at a min. of 20cm.
(2) Leakage Current and Solution
The existence of earth capacitance/wire-to-wire capacitance of cables on the input/output side of
the inverter and earth capacitance of the motor may induce leakage current. Leakage current includes
earth leakage current and wire-to-wire leakage current, the intensity of which depends on the numerical
value of distributed capacitance and carrier frequency.
