Sharing The Dc Bus; Dc Busbar Connection - Baldor MotiFlex e100 Installation Manual

3.5 Sharing the DC bus

The AC power supply is rectified and smoothed within the MotiFlex e100 to create a typical 'DC
bus' voltage of around 678 VDC (when using a 480 VAC supply). The DC bus voltage is then
switched by a power module to create the UVW output waveforms that drive the motor. The
MotiFlex e100 is capable of sharing its DC bus voltage with similar drives mounted beside it, using
solid metal busbar connections between the drives. In a group of drives, this significantly reduces
the amount of AC power supply wiring, filters, fuses and breakers, since these are only required
by the single drive that is generating the DC bus voltage (the source drive). Furthermore, only one
regeneration resistor is required for the group (see section 3.8). The DC bus outputs are
conditionally short-circuit proof according to EN61800-5-1, 6.2. When sharing the DC bus, revised
AC input current ratings apply. See section 8.

3.5.1 DC busbar connection

Hazardous voltages exist underneath the drive's hinged top cover! Before
lifting the cover ensure that AC power has been removed from the source
drive and at least 5 minutes have elapsed to allow the DC bus output
DANGER
capacitors to discharge.
Always observe the correct polarity. The busbar nearest the front of the
MotiFlex e100 is positive. The busbar at the rear is negative, as shown in Figure 5.
WARNING
When sharing the DC bus, special care must be taken to calculate the total peak and
continuous supply current requirement of the drives, since they will all derive power
from the source drive's DC bus.
NOTICE
Only the source drive must be connected to the AC power source so that it can
generate the DC bus voltage. The receiving drives sharing the DC bus must not be
connected to the AC power source.
NOTICE
In the unlikely event that one of the MotiFlex e100's DC bus capacitors should fail
with a short circuit, an internal fast-acting fuse will trip. These fuses are not user
replaceable. Similar fuses in other drives sharing the DC bus are also likely to trip.
NOTICE
The top panel of the MotiFlex e100
incorporates a cover that conceals the DC
busbar output pads. To allow sharing of the
DC bus, optional busbar kits (Baldor parts
OPT-MF-DC-A, -B, -C or -D) must be
attached to these pads using the screws
supplied with the busbars. Lift the front
edge of the cover to access the DC bus
output pads. Since the busbars have a
fixed length, accurate positioning of
adjacent drives is critical to ensure the
busbars will fit. See section 3.2.4 for
details of busbars and fitting dimensions.
MN1943
Figure 11 - Shared DC bus connections
Basic Installation 3-23
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