Noise Reduction Techniques - Mitsubishi Electric -MR-CV User Manual

10.5

Noise reduction techniques

Noises are classified into external noises, which enter the converter unit/drive unit to cause it to malfunction, and those
radiated by the converter unit/drive unit to cause peripheral equipment to malfunction. Because the converter unit/drive unit is
an electronic device that handles small signals, the following general noise reduction techniques are required.
The drive unit can also be a source of noise as its outputs are chopped by high carrier frequencies. If peripheral equipment
malfunctions due to noise produced by the servo amplifier, take measures to reduce the noise. The reduction techniques will
vary slightly with the routes of noise transmission.
Noise reduction techniques
■General reduction techniques
• Avoid bundling power lines (input/output lines) and signal cables together or running them in parallel to each other.
Separate the power lines from the signal cables.
• Use a shielded twisted pair cable for connection with the encoder and for control signal transmission, and connect the
external conductor of the cable to the SD terminal.
• For grounding, refer to the following.
Page 63 Grounding
■Reduction techniques for external noises that cause the converter unit/drive unit to
malfunction
If noise sources (such as a magnetic contactor, an electromagnetic brake, and many relays) are generating a large amount of
noise near the converter unit/drive unit and the converter unit/drive unit may malfunction, the following countermeasures are
required.
• Provide surge killers on the noise sources to suppress noise.
• Attach data line filters to the signal cables.
• Ground the shields of the encoder connecting cable and the control signal cables with cable clamp fittings.
• Although a surge absorber is built into the converter unit, to protect the converter unit/drive unit and other equipment
against large exogenous noise and lightning surge, attaching a varistor to the power input section of the equipment is
recommended.
10 OPTIONS AND PERIPHERAL EQUIPMENT
96
10.5 Noise reduction techniques