Grounding - Mitsubishi Electric Melservo-J4 MR-J4-DU*B4-RJ100 Series Instruction Manual

3.3

Grounding

WARNING
• Ground the power regeneration converter unit, drive unit, and servo motor securely.
• To prevent an electric shock, be sure to connect the protective earth (PE) terminal (marked
the protective earth (PE) of the cabinet.
For items other than the ones described in this section, refer to section 3.3 in "MR-CV_/MR-CR55K_/MR-J4-
DU_(-RJ) Instruction Manual".
Capacitances exist between input/output lines of the servo and other lines or the ground, and in the servo motor, through
which a leakage current flows. For a servo with a large capacity, a leakage current including a high-frequency of several 100
mA may flow.
Note the following.
• To prevent an electric shock, be sure to ground the drive unit, power regeneration converter unit, and servo motor.
• To lower the impedance of the grounding wire, use the wire of the size equal to or greater than that shown in section 8.4 in
"MR-CV_/MR-CR55K_/MR-J4-DU_(-RJ) Instruction Manual", and make the wire as short as possible. Stranded wires or
braided wires are helpful to lower impedance.
• Prevent multiple points from being grounded. Ground one point. Grounding multiple points may generate a potential
difference between the grounded points by the impedance of the grounding wires. If the units cannot be grounded to one
point, connect the grounding wires to a copper bar and ground it to one point.
Converter Drive Converter
unit unit
• Leakage currents including high-frequency components flow through the grounding wires of the drive unit, power
regeneration converter unit, and servo motor. Route the grounding wires of noise-sensitive devices separately.
Converter Drive
unit unit
Good example
• Route the grounding wires as far away from the input/output lines of noise-sensitive devices as possible, and run the
grounding wires in parallel to each other as short as possible.
• Connect the grounding wire from the servo motor to the protective earth (PE) terminal of the drive unit. Put the grounding
wires of the drive unit and the power regeneration converter unit together into one on the protective earth (PE) terminal of
the cabinet, and then connect to the ground. Connect the grounding wire of the servo motor to only the drive unit of the
encoder master servo amplifier. If the grounding wire of the servo motor is connected to two or more drive units, the
circulating current may pass through the grounding wire depending on wiring conditions. When connecting grounding wires
to two or more drive units, be sure to twist the wires of the drive unit power outputs (U/V/W).
Drive Converter
unit unit
Other Converter
device
) of the power regeneration converter unit and the drive unit to
Drive Converter
unit unit unit
Drive Other
unit unit device
Bad example
Drive
unit
Copper bar
3 SIGNALS AND WIRING
3.3 Grounding
3
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