Rockwell Automation SA500 DC Bus Supply - Manual (Page 9)

Introduction 1-1
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HAPTER
1
Introduction
Distributed Power System (DPS) SA500 DC Bus Supplies rectify three-phase AC
input voltage and provide constant DC voltage to the SA500 AC Power Modules. The
DC bus supplies also contain circuits that permit regeneration from the SA500 AC
Power Modules during motor deceleration or overhauling.
The main circuit, which supplies motoring current, consists of a full-wave bridge made
from three SCRs in the upper legs and three diodes in the lower legs. The SCRs are
gradually phased on to provide pre-charging and are fully turned on during normal
operation.
The regenerative circuit consists of a transistor and a resistor in series across the DC
bus. It is switched on when the bus voltage is higher than the AC line feeding the
bridge and turned off when the bus voltage has dropped to an acceptable level.
The DC bus supplies require no programming or user tuning. These are self-contained
units that provide full regulation and diagnostic capabilities.
The four DC bus supply models are listed in table 1.1.
Input power for the bus supplies may be either isolated or non-isolated three-phase
230 VAC. Output power from the bus supplies is nominally 325 VDC with 230 VAC
input power. A single Bus Supply can power up to six SA500 AC Power Modules.
Refer to section 3.1 for more information on selecting a bus supply.
Note that throughout this manual references to a “bus supply” apply to all four bus
supplies unless stated otherwise.
Table 1.1 – SA500 DC Bus Supplies
Model Number
Output Amps
(DC) Description
615055-2R 50 A DC Bus Supply with internal braking resistor
615055-2T 50 A DC Bus Supply with user-supplied, external
braking resistor(s)
615055-2S 100 A DC Bus Supply with internal braking
resistor(s)
615055-2V 100 A DC Bus Supply with internal braking
resistor(s)