Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 114)

114 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
5. The drive precharge delay must be completed. After conditions 1 through
4 above are met, the time delay set in parameter 472 [PreCharge Delay]
must be completed before the precharge device bypass is commanded. If
any of the above conditions become false during the precharge delay
period, the delay timer is reset. If parameter 472 [PreCharge Delay] is set
less than 200 ms, then an internal 200 ms delay is used. [PreCharge Delay]
has a calculated maximum value based on parameter 410 [PreChrg
TimeOut]; [PreCharge Delay] = [PreChrg TimeOut] - 1.0 second. (Also
see
Precharge Staging on page 116 for common and shared bus drives
below).
Precharge Control Functional Diagram
Precharge Timeout Fault
The precharge control logic has an associated precharge timeout fault to alert the
user if the precharge has not completed within the timeout period. Parameter 381
[PreChrg Err Cnfg] provides the configuration control for the precharge timeout
fault. Parameter 410 [PreChrg TimeOut] sets the period or delay for this timeout
fault (default = 30 seconds). The timeout timer is not started until the user
requests a precharge either through the hardware input (digital input) or through
parameter 411 [PreChrg Control]. The precharge timeout fault is intended only
to alert the user that there may be a problem in the precharge control. The
precharge fault, for the most part, does not affect the precharge operation. If
conditions change to complete or restart precharge, the precharge control will
function as described above independent of whether or not a precharge timeout
fault has occurred.
If the drive does not complete precharge due to an unstable bus voltage, then after
the precharge timeout period, the precharge control will complete precharge,
provided all of the other conditions for precharge are met. This control is based
on the precharge timeout status and is independent of whether or not the
precharge timeout is configured as a fault, alarm or ignored. This feature could be
useful in cases where bus disturbances are created by another drive in a common
or shared bus installation.
S
R
Precharge Request
PreCharge Delay Timer
(P472)
Reset
Precharge Done
(P555 bit 11)
1
Digital Input "30"
Digital Input =
30 "PreChrg En"
PreChrg Control (P411)
1=Enable, 0 = Hold PreChrg
Ride Through Active
Enabled (PWM Active)
Low Bus Voltage
Bus Voltage Stable
SET
CLR
Q
Q
S
R
SET
CLR
Q
Q