Emerson Unidrive M700 Installation Manual page 73

4.12.6 Variations in the EMC wiring
Interruptions to the motor cable
The motor cable should ideally be a single length of shielded or armored cable having no
interruptions. In some situations it may be necessary to interrupt the cable, as in the following
examples:
• Connecting the motor cable to a terminal block in the drive enclosure
• Installing a motor isolator / disconnect switch for safety when work is done on the motor
In these cases the following guidelines should be followed.
Terminal block in the enclosure
The motor cable shields should be bonded to the back-plate using uninsulated metal cable-clamps
which should be positioned as close as possible to the terminal block. Keep the length of power
conductors to a minimum and ensure that all sensitive equipment and circuits are at least 0.3 m (12
in) away from the terminal block.
Figure 4-21 Connecting the motor cable to a terminal block in the enclosure
Using a motor isolator / disconnect-switch
The motor cable shields should be connected by a very short conductor having a low inductance.
The use of a flat metal coupling-bar is recommended; conventional wire is not suitable.
The shields should be bonded directly to the coupling-bar using uninsulated metal cable-clamps.
Keep the length of the exposed power conductors to a minimum and ensure that all sensitive
equipment and circuits are at least 0.3 m (12 in) away.
The coupling-bar may be grounded to a known low-impedance ground nearby, for example a large
metallic structure which is connected closely to the drive ground.
Figure 4-22 Connecting the motor cable to an isolator / disconnect switch
From the
Drive
Unidrive M/HS Frame 3 and 4 Power Installation Guide
Issue Number: 3
From the Drive
Back-plate
Enclosure
To the motor
Isolator
Coupling bar
To the
motor
(If required)
73