VD520 Series Inverter User Manual EMC Guide
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placed nearby the inverter or together with the inverter in the same control cabinet, they are easy to
suffer interference and thus generate error actions. It is recommended to handle with the following
methods: Put in places far away from the interference source; do not arrange the signal cables with
the power cables in parallel and never bind them together; both the signal cables and power cables
employ shielded cables and are well earthed; install ferrite magnetic ring (with suppressing frequency
of 30 to 1, 000MHz) at the output side of the inverter and wind it 2 to 3 cycles; install EMC output filter
in bad conditions;
2) When the equipment suffering interferences and the inverter use the same power supply, it may
cause conduction interference. If the above methods cannot remove the interference, it shall install
EMC filter between the inverter and the power supply (refer to Section for the prototyping operation);
3) The surrounding equipment is separately earthed, which can avoid the interference caused by the
leakage current of the inverter’s earth wire when common earth mode is adopted.
7.3.5 Leakage Current and Disposal
Inverter leakage current has two types: one is to ground leakage current, one is line-to-line leakage
current.
1)
The factors of affecting to ground leakage current and solution:
the conducting cable and earth has distributed capacitance, the bigger the capacitance is, the bigger
the leakage current is, so by effectively shorten the distance between motor and inverter can reduce
distributed capacitance. The bigger the carrier frequency is, the bigger the leakage current is. By
reducing carrier frequency to reduce leakage current, but reducing carrier frequency will result in
motor noise increasing. Please pay attention: add electric reactor is also an effective way to solve
leakage current. The leakage current will increase as the increase of loop circuit current. So if motor
power is big, the corresponding leakage current is big.
2)
The factors resulting in line-to-line leakage current and solution:
There is distributed capacitance among inverter output wirings, if the passing current has higher
harmonic, it may result in resonance and bring leakage current. If using thermal relay might result in
wrong action. The solution is to reduce carrier frequency or add output electric reactor. In application,
it is not recommended to add thermal relay between motor and inverter, but to use inverter electronic
overcurrent protection function.
7.3.6 Notice for Power Input Side adding EMC Input Filter
WARNING
!
● When using the filter, please follow its rated values strictly. Since the filter belongs to Classification I
electric appliances, the metal enclosure of the filter shall be large and the metal ground of the
installing cabinet shall be well earthed and have good conduction continuity. Otherwise there may be
danger of electric shock and the EMC effect may be greatly affected.
● Through the EMC test, it is found that the filter ground must be connected with the PE end of the
inverter at the same public earth. Otherwise the EMC effect may be greatly affected.
● The filter shall be installed at a place close to the input end of the power supply as much as
possible.
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