Accelnet & Stepnet Plus Panels User Guide
16-01339 Rev 07
DC
P
OWER
G
ROUNDING
The graphic below shows the basic elements of a DC power supply system for a Plus Panel drive. The Plus
Panel drives are Protective Class I equipment in regards to protection against electric shock. Accordingly, the
drives have both basic insulation between circuits and accessible conductive parts and a means of connecting
a protective earthing conductor to prevent accessible conductive parts from becoming hazardous live in the
event of a failure of the basic insulation. A protective earthing conductor must be connected to the drive at the
grounding stud on the drive marked with the PE (Protective Earth) symbol. Note that the Plus Panel drives
require that the DC power supply be galvanically isolated from AC mains as shown in the figure below.
The PE marking is shown to illustrate the point for connecting the protective earth conductor to the drive. Aside
from the electrical safety aspects of grounding, attention must also be paid to the wiring and grounding
practices required to reduce susceptibility to external EMI (Electro-Magnetic Interference) sources, to suppress
EMI emissions, and to minimize differences in signal grounds due to cable length and equipment connections.
The (-) terminal of the power supply is connected by a short, direct path to the equipment ground terminal
(sometimes called the “star” or equipment ground). This practice is common when drives are in the same
cabinet with short connections to the drives.
The DC power wiring is shown as a shielded, twisted pair of a gauge suitable for the input current rating of the
drive. The shield should connect to the (-) terminal of the power supply on one end, and to a screw that holds
the heatplate to the mounting plate for best results. This connection will provide the lowest impedance path
between the power supply and drive for noise originating in the drive. Doing so will minimize noise currents
flowing in the mounting plate or the cabinet.
Note that in order to meet conducted emissions requirements, an EMI filter is needed between the +HV input of the
drive and the output of the power supply as shown above. Details on EMI filter requirements are given in sections 5.4
and 5.5.
M
OTOR
C
ONNECTION
G
ROUNDING
On BEL/BPL/BML, the Frame Ground terminal at J7-1 connects to the drive chassis.
On BE2/BP2, the Frame Ground terminal at J9-1 and J10-1 connects to the drive chassis.
These ground terminals are provided as cable shield and protective earth connection points for the motor
cables. Connection of cable shields to these points is made to provide electrical noise reduction. Connection
of motor cable protective earth conductors to these points is made to prevent the motor housing from becoming
hazardous live in the event of an insulation failure. Protective earth connections for the motor housings are
subject to local electrical codes and must be reviewed for compliance with those codes. It is the responsibility
of the end user to ensure compliance with local electrical codes and any other applicable standards. It is
strongly recommended that motor also be connected to protective earth connection points located as close to
the motor as possible. In many applications, the machine frame is used as a primary or supplemental protective
earth connection point for the motor housings.
