Rockwell Automation 2364P Parallel DC Bus Supply Config. - Manual (Page 19)

Publication 2364P-5.01 December 1999
Theory of Operation 1-7
Output of NRU//RGU Configurations
The RGUs supply up to 10% of their rated amperes as motoring
current. In this first 10%, the RGUs will regulate the voltage to 1.52
times the line voltage, the voltage on the DC bus will be greater than
the AC line, and the diodes in the NRU will not conduct.
Figure 1.10
RGU Motoring–Load Up To 10% of RGU Rating
When the load increases beyond the first 10%, the RGU is no longer
able to regulate the voltage (since the current limit is set to 10%), and
the bus voltage drops to a level where the diodes in the NRU can
conduct. The NRU then supplies the motoring current for the
remainder of the load, resulting in a bus voltage of 1.35 times the line
voltage.
Figure 1.11
RGU and NRU Motoring–Load Over 10% of RGU Rating
When the load drops under the 10% capability of the RGUs, the
RGUs will begin to regulate the bus voltage again to 1.52 times the
line voltage, and the diodes in the NRU will stop conducting.
1.52 x A C Lin e
V oltag e
R GU N R U
3-Ph as e
A C Lin e
C u rren t
(Up to 1 0% of th e
R GU ra tin g )
N o
Cu rre n t
v
V
greater voltage
smaller voltage
1.35 x A C Lin e
V oltag e
R GU N R U
3-Ph as e
A C Lin e
Cu rre n t
(10 % o f th e
RG U ratin g )
Cu rre n t
v
V