Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 115)

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 115
Detailed Drive Operation Chapter 1
Settings for parameter 381 [PreChrg Err Cnfg]:
0 “Ignore”: This setting disables the precharge timeout fault. In this case the drive
ignores condition three of the precharge operation (described on
page 112 ) so
that the drive does not check for an unstable bus voltage. Therefore, after the
precharge timeout period the precharge control will complete precharge,
providing all of the other conditions for precharge are met. This feature could be
useful in cases where bus disturbances are created by another drive in a common
or shared bus installation.
1 “Alarm”: If precharge does not complete within the timeout period, the drive
does not fault, but it sets an alarm bit in parameter 326 [Alarm Status 1], bit 30
“Precharge Er”.
2 “FltCoastStop”: This is the factory default setting. If precharge does not
complete within the timeout period, the drive faults and disables the PWM
output.
External Precharge
In cases where the user must provide external drive precharge hardware and
control, the following should be considered:
• The current limit necessary to protect the drive and fuses
• The breaking capability of the precharge device
• The regenerative capability of the drive/system
• Whether or not ride through control will be accommodated
• Impedance isolation that may be needed between drives
• Braking requirements
• Sharing between drives
• The power disconnect operation in the system
The drive's precharge and ride through functions will still run even though the
actual precharge hardware is not controlled by the drive. The drive's enable
(parameter 155 [Logic Status], bit 0 “Active”), precharge enable (controlled with
a digital input or parameter 411 [PreChrg Control]) and precharge done
(parameter 555 [MC Status], bit 11 “PreChrg Done”) parameters are available
for the external precharge/ride through control in cases where the users would
like to provide coordinated operation between the external precharge and the
drive's ride through operation.