Remedies For The Interference From The Inverter To The Surrounding; Electromagnetic Equipment; Remedies For Leakage Current; Precautions On Installing Emc Input Filter At The Input End Of Power Supply - Powtran PI500-S Series Manual

Chapter 6 Troubleshooting

6-3-4.Remedies for the interference from the inverter to the surrounding

electromagnetic equipment

These noise interference are classified into two types: one is the radiation interference of the
inverter, and the other is the conduction interference of the inverter. These two types of interference
cause that the surrounding electric equipment suffer from the affect of electromagnetic or
electrostatic induction. Further, the surrounding equipment produces error action. For different
interference, please refer to the following remedies:
1) Generally the meters, receivers and sensors for measuring and testing have more weak
signals. If they are placed nearby the inverter or together with the inverter in the same control
cabinet, they easily suffer from interference and thus generate error actions. It is recommended to
handle with the following methods: away from the interference source as far as possible; do not
arrange the signal cables with the power cables in parallel and never bind them together; both the
signal cables and power cables shall use shielded cables and shall be well grounded; 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 turns; install EMC output filter in more severe conditions.
2) When the interfered equipment 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 6.3.6 for the selection operation);
3) The surrounding equipment shall be separately grounded, which can avoid the interference
caused by the leakage current of the inverter's grounding wire when common grounding mode is
adopted.

6-3-5.Remedies for leakage current

There are two forms of leakage current when using the inverter. One is leakage current to the
earth, and the other is leakage current between the cables.
1) Factors of affecting leakage current to the earth and its solutions:
There are the distributed capacitance between the lead cables and the earth. The larger the
distributed capacitance, the larger the leakage current; the distributed capacitance can be reduced
by effectively reducing the distance
between the inverter and the motor. The higher the carrier frequency, the larger the leakage
current. The leakage current can be reduced by reducing the carrier frequency. However, the carrier
frequency reduced may result in
the increase of motor noise.Please note that additional installation of reactor is also an
effective method to solve leakage current problem.
The leakage current may increase with the increase of circuit current. Therefore, when the
motor power is higher, the corresponding leakage current will be higher too.
2) Factors of producing leakage current between the cables and its solutions:
There is the distributed capacitance between the output cables of the inverter. If the current
passing lines has higher harmonic, it may cause resonance and thus result in leakage current. If the
thermal relay is used, it may generate error action.
The solution is to reduce the carrier frequency or install output reactor. It is recommended that
the thermal relay shall not be installed in the front of the motor when using the inverter, and that
electronic over current protection function of the inverter shall be used instead.

6-3-6.Precautions on installing EMC input filter at the input end of power supply

1) Note: when using the inverter, please follow its rated values strictly. Since the filter belongs
to Classification I electric appliances, the metal enclosure of the filter and the metal ground of the
installing cabinet shall be well earthed in a large area, 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 end and the PE end of the inverter must be
connected to the same public earth end, otherwise the EMC effect may be greatly affected.
2) 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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