Noise; Principles Of Noise Generation - Mitsubishi Electric FATEC FR-A800 Manual

7
REVIEW OF INSTALLATION ENVIRONMENT
7.2

Noise

As electronic devices is widely used, troubles due to the noise tend to increase.
Since an inverter generates the noise in accordance with the operating principle, it may affect
adjacent devices.
The influence rate varies depending on circumstances such as the inverter control method, noise
capacity of the adjacent device, wiring status, installation interval, and earthing (grounding) method.
However, when installing the following devices around the inverter, it is recommended to take the
countermeasures described hereafter according to the circumstances.
[Devices for which considering countermeasures against noise is required]
Sensors (such as proximity switches), video cameras (such as ITVs and image scanners),
wireless communications devices (including AM radios), sound equipment (such as microphones,
videos, and audio equipment), CRT display devices, and medical devices
[Devices for which considering countermeasures against noise is recommended]
Instruments and internal telephones
7.2.1

Principles of noise generation

The inverter controls output voltage waveform by switching the DC voltage in a high speed.
Precipitous rising and falling of the output waveform contain many high frequency components.
These high frequency components are the source of the noise.
The noise generated in such a case and the harmonics described in Section 7.1 may be confused
because both of them may affect other electronic devices. However, harmonics are typically 40th to
50th (2.4 to 3 kHz), and noise is several 10 kHz or more.
Fig. 7.11 Actual measurement example of output current and voltage waveform of the inverter FR-A800 series
7.2 Noise
102
(When carrier frequency is 2 kHz)
2 ms/DIV