Mitsumi electronic FR-F520-0.75K, 55K Inverter-generated noises and reduction techniques

INSTALLATION AND WIRING

2.3.3 Inverter-generated noises and reduction techniques

Some noises enter the inverter causing it to misoperate and others are radiated by the inverter causing misoperation of peripheral devices. Though the inverter is designed to be insusceptible to noise, it handles low-level signals, so it requires the following basic measures to be taken. Also, since the inverter chops the output at a high carrier frequency, it could generate noise. If these noises cause peripheral devices to misoperate, measures should be taken to suppress the noise. The measures differ slightly depending on noise propagation paths.

1)Basic measures

•Do not run the power cables (I/O cables) and signal cables of the inverter in parallel with each other and do not bundle them.

•Use twisted shielded cables for the detector connection and control signal cables and connect the sheathes of the shielded cables to terminal SD.

•Ground the inverter, motor, etc. at one point.

2)Measures against noises which enter and cause misoperation of the inverter

When devices which generate many noises (which use magnetic contactors, magnetic brakes, many relays, for example) are installed near the inverter and the inverter may be effected by noise, the following measures must be taken:

•Provide surge suppressors for devices that generate noise to suppress noise.

•Fit data line filters (refer to page 33) to signal cables.

• Ground the shields of the detector connection and control signal cables with cable clamp metal. 2

3)Measures against noise, which is radiated by the inverter causing misoperation of peripheral devices. Inverter-generated noise is largely classified into those radiated by the cables connected to the inverter and inverter main circuit (I/O), those electromagnetically and electrostatically inducted to the signal cables of the peripheral devices close to the main circuit power supply, and those transmitted through the power supply cables.

Inverter-generated noise

Air-propagated		Noise directly radi-	Path 1)
noise		ated by inverter
		Noise radiated by	Path 2)
		power cables
		Noise radiated by	Path 3)
		motor cables
Magnetic induction	Path 4),5)
noise
Static induction	Path 6)
noise
Cable-propagated		Noise propagated
		through power	Path 7)
noise
		cables
		Noise from ground
		cable due to	Path 8)
		leakage current

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