Mitsubishi Electric FATEC FR-A800 Manual page 120

7
REVIEW OF INSTALLATION ENVIRONMENT
(b) This inverter must be earthed (grounded). Earthing (grounding) must conform to the
requirements of national and local safety regulations and electrical codes. (NEC section 250,
IEC 61140 class 1 and other applicable standards).
A neutral-point earthed (grounded) power supply must be used for 400 V class inverter to be
compliant with EN standard.
(c) Use the thickest possible earthing (grounding) cable. The earthing (grounding) cable should
be no less than the size indicated in the Instruction Manual.
(d) The earthing (grounding) point should be as close to the inverter as possible, and the earth
(ground) wire length should be as short as possible.
(e) Run the earthing (grounding) cable as far away as possible from the I/O wiring of the noise-
sensitive devices, and run them in parallel in the minimum distance.
(f) For the earth (ground) terminal of the motor, use one cable of the 4-core cable and earth
(ground) at the inverter side.
When earthing (grounding) of the inverter, motor driven by the inverter, and devices such as audio
devices, sensors, and computers are connected together, the leakage current becomes the noise
source and the noise that affects the devices.
To resolve this problem, separate the dirty earth (ground) for the inverter and the clean earth (ground)
for devices such as audios, sensors, and computers.
Current
0
0.4 ms
Fig. 7.27 Example of the earthing (grounding) cable current of the inverter-driven motor
(Inverter: 200 V class 0.75 K, Motor: SF-JR 0.75 kW 4 P)
Time
7.2 Noise
1
2
3
4
5
6
7
8
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