Rockwell Automation 2364F Regenerative DC Bus Supply Unit (RGU) - Manual (Page 26)

Publication 2364F-5.01– October 2003
1-10 Overview
What Happens When 3-Phase
Power is Applied to the RGU and
the Door-Mounted Start Switch is
Turned On? When the RGU’s disconnect is closed and the start switch is
turned on, the RGU will begin its precharge routine. This
routine charges the DC bus capacitor bank in a controlled
fashion.
Precharge Operation for J, K, L, and M-Code RGUs
Two contactors (M1 and M2) are used to perform the precharge
operation in the J, K, L, and M-code RGUs.
When the disconnect (MCP1 or CB1) is closed and the start switch is
turned on, the main contactor (M1) remains open, the precharge
contactor (M2) closes, and current begins to flow through the
precharge circuit (bypassing the main 3-phase circuit). This
precharge circuit (which has a resistive load) charges up the capacitor
bank. As the bank approaches capacity, the main contactor (M1)
closes, the precharge contactor (M2) opens, and normal operation
begins.
Figure 1.6
Precharge Circuit (J, K, L, and M-Code RGUs)
D C
B us
C ircuit B reaker
or M C P
(C B 1 or M C P1)
Pow er Structure
+
-
C apacitor
B ank
M ain
C ontactor
(M 1)
Precharge Circuit
Precharge
C ontactor
(M 2)
R
Note: All J-code RGUs have a single phase
precharge circuit (on L1 and L2). Older K-N
code units may also have a single-phase
precharge circuit.