Variations In The Emc Wiring; Interruptions To The Motor Cable; Terminal Block In The Enclosure; Using A Motor Isolator / Disconnect-Switch - Emerson Powerdrive F300 User Manual

Safety Product Mechanical
information information installation
°
A complete 360 termination of the shield to the terminal housing of the
motor is beneficial.
From an EMC consideration it is irrelevant whether the motor cable
contains an internal (safety) ground core, or if there is a separate
external ground conductor, or where grounding is through the shield
alone. An internal ground core will carry a high noise current and
therefore it must be terminated as close as possible to the shield
termination.
Figure 4-40 Grounding the motor cable shield
Unshielded wiring to the optional braking resistor(s) may be used
provided the wiring runs internally to the enclosure.
If the control wiring is to leave the enclosure, it must be shielded and the
shield(s) clamped to the drive using the grounding bracket as shown in
Figure 4-41. Remove the outer insulating cover of the cable to ensure
the shield(s) make direct contact with the bracket, but keep the shield(s)
intact until as close as possible to the terminals
Alternatively, wiring may be passed through a ferrite ring, part number
3225-1004.
Figure 4-41 Grounding of signal cable shields using the
grounding bracket
96
Electrical Getting Basic
installation started parameters
Running NV Media Card
Optimization
the motor Operation
4.10.7

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 4-42 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 4-43 Connecting the motor cable to an isolator /
disconnect switch
From the
Drive
Surge immunity of control circuits - long cables and
connections outside a building
The input/output ports for the control circuits are designed for general
use within machines and small systems without any special precautions.
These circuits meet the requirements of EN 61000-6-2:2005 (1 kV
surge) provided the 0 V connection is not grounded.
Onboard Advanced Technical
PLC parameters data
From the Drive
Back-plate
Enclosure
To the motor
Isolator
Coupling bar
(If required)
Powerdrive F300 User Guide
UL listing
Diagnostics
information
To the
motor
Issue Number: 2