A rigid metal conduit can be used as the shield of the motor wires. Always
observe the following points:
• Remove all paint from the control cabinet and motor housing where
the conduit is fastened.
• Securely fasten all conduit ttings.
• Run only the motor wires through the conduit, all other wires, high voltage
AC and low voltage signal, should be pulled through a separate conduit.
• Connect the control panel to the Sub-panel with a heavy ground strap.
Should EMI lters be used, they should be mounted to the inverter or as close
as possible to the inverter and on the same sub-panel as the inverter. Good
metallic surface contact to the sub-panel is required to provide adequate high-
frequency grounding of the lter. Always use the shielding plate provided with
the lter when connecting the lter to the inverter.
Shielding of control wires:
• If digital signal wires are terminated on a terminal block in the control
panel, the shields should be rmly connected to the sub-panel on both
sides of the terminal block.
• The shields of digital signal wires originating outside the control cabinet,
which are not terminated on a terminal block, must be connected to the
sub-panel at the point where the cable enters the control panel and at
the inverter.
• If the shield is terminated to the sub-panel within 8 inches (20cm) of the
inverter, then the shield no longer needs to be connected to the inverter.
• When using un-shielded signal wires, they should always be installed
as a twisted pair (signal and common).
• Low voltage signal wires should cross high voltage wires at right angles.
Electrical Connection
18
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