Owner manual

Publication 2364P-5.01 December 1999
1-2 Theory of Operation
Parallel configurations use the following front-end units:
• Regenerative DC Bus Supply Unit (RGU)
• Non-Regenerative DC Bus Supply Unit (NRU)
Each parallel configuration will include one, two, or three
Regenerative DC Bus Supply Units (RGUs). These units are used to
supply motoring current to the DC bus, and are used to regenerate
current back onto the AC line.
Most of the parallel configurations will also include a
Non-Regenerative DC Bus Supply Unit (NRU) to supply the
motoring current to the DC bus.
Note: When there is an NRU in the configuration, the NRU
supplies motoring current while the RGUs regenerate most of the
excess capacity (the RGU also contributes 10% of its rated
motoring current to the DC bus).
Figure 1.2
NRU and RGU Operation
RGU
Motoring
Current
Regenerating
Current
NRU RGU
3-Phase
AC Line
DC Supply for
Drive Lineup
10%
Motoring
Current
Regenerating
Current
Motoring
Current
RGU
3-Phase
AC Line
DC Supply for
Drive Lineup
Motoring
Current
Regenerating
Current
NRU//RGU Configuration
RGU//RGU Configuration