Rockwell Automation SA3100 AC Power Modules - Manual (Page 113)

SA3100 Internal DC Bus Control F-3
Note that the bit must be turned on before the programmer enables the bridge test of
the inner control loop in the PMI processor in register 100/1100. If BUS_ENA@ is not
enabled first, an interlock error will occur (register 205.1205, bit 6, IC_BUS@) and the
drive will not be permitted to execute either the bridge test or the control loop.
In response to the rising edge of the BUS_ENA@ bit, the PMI processor will allow the
bus voltage to rise above the undervoltage threshold and then turn on the pre-charge
semiconductor (Low voltage B frame Power Modules or common bus C frame or
larger units). This will short out the pre-charge resistors. The PMI processor will set
BUS_RDY@ (bit 4 in register 200/1200) when all of the following conditions have
occurred:
• the internal DC bus has been enabled via the BUS_ENA@ input
• the internal DC bus voltage has reached the level specified in the tunable variable
UVT_E0%
• the internal DC bus voltage is at steady state
• the pre-charge semiconductor is on
The BUS_ENA@ bit must remain on during the bridge test or the execution of
the control algorithm in the PMI processor, or the pre-charge semiconductor
will be turned off and the drive will shut down. If BUS_ENA@ is turned off at any
time, power to the power device gates is shut off. Approximately one second later, the
pre-charge semiconductor is turned off. If the pre-charge contactors close when they
are not commanded to do so by the PMI processor, register 202/1202, bit 6
(FLT_CHG@) is set and the drive is shut down.
There is a time limit of 10 seconds from the time when the rising edge of the
BUS_ENA@ input is detected to the time when the bus voltage must reach the steady
state voltage specified in the tunable variable UVT_E0% (See the following section for
more information on tunable variable UVT_E0%). If this time limit is exceeded, the
pre-charge semiconductor is turned off and the FLT_CHG@ bit (register 202/1202, bit
6) is set. If the bus voltage recovers to the appropriate level within 10 seconds, the
pre-charge semiconductor will be turned on and the drive will resume operation.
Refer to the internal DC bus flowchart (figure F.3) for more detailed information.