Chapter 6 Troubleshooting
127
Ch
ap
ter 6
6-3.
EMC directive
6-3-1.
Harmonic effect
The higher harmonics of power supply may damage the inverter. Thus, at some places where the
quality of power system is relatively poor, it is recommended to install AC input reactor.
6-3-2.
Electromagnetic interference and installation precautions
There are two kinds of electromagnetic interference, one is the interference from electromagnetic
noise in the surrounding environment to the inverter, and the other is the interference from the inverter
to the surrounding equipment.
Installation Precautions:
1)The earth wires of the Inverter and other electric products ca shall be well grounded;
2)The power cables of the inverter power input and output and the cable of weak current signal
(e.g. control line) shall not be arranged in parallel but in vertical if possible.
3) It is recommended that the output power cables of the inverter shall use shield cables or steel
pipe shielded cables and that the shielding layer shall be grounded reliably, the lead cables of the
equipment suffering interferences shall use twisted-pair shielded control cables, and the shielding
layer shall be grounded reliably.
4)When the length of motor cable is longer than 30 meters, it needs to install output filter or
reactor.
6-3-3.
Remedies for the interference from the surrounding
electromagnetic equipment to the inverter
Generally the electromagnetic interference on the inverter is generated by plenty of relays,
contactors and electromagnetic brakes installed near the inverter. When the inverter has error action
due to the interference, the following measures is recommended:
1) Install surge suppressor on the devices generating interference;
2) Install filter at the input end of the inverter, please refer to Section 6.3.6 for the specific
operations.
3) The lead cables of the control signal cable of the inverter and the detection line shall use the
shielded cable and the shielding layer shall be grounded reliably.
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.
