Rockwell Automation WebPak 3000 DC Drive Application Workbook Version 1.1 - Manual (Page 27)

Configuring the Speed Loop 3-17
3.5.2 The Current Memory Function
The transfer dynamics of some unwind and winder designs will require an operating
mode change from the primary outer control loop regulator to an interim current loop
regulator. This regulator transition is necessary when the primary loop regulator
feedback device (load cell or dancer) becomes mechanically isolated at some point in
the transfer sequence.
The current memory function places the drive in a current regulator mode with a fixed
reference. The state of the current memory command is displayed in
CURRENT MEM
COMMAND (P.319).
þ
To enable the current memory function:
▲
Set CURRENT MEMORY ENABLE (P.314) to ENABLE .
The output of the speed loop PI block, SPD LOOP OUTPUT (P.299) is captured
and held when the digital input CURRENT MEMORY DIN TP (P.499) is asserted.
The value for current memory will equal the last value of P.299, prior to the
assertion of P.499. However, the value can be modified by
CURRENT MEMORY
BOOST (P.313) over a range of 75% to 150%.
þ
To modify the current memory value in SPD LOOP OUTPUT (P.299):
▲
Set CURRENT MEMORY BOOST (P.313).
!
ATTENTION: The current memory funciton places the drive in a current
regulator mode with a fixed reference. The user must ensure that the
motor is properly loaded or provide external overspeed protection to
avoid an unsafe speed condition. It is also recommended that an external
timer limit the kength of time the drive may be held in current memory to
prevent damage to the motor. Failure to observe this precaution could
result in severe bodily injury or loss of life.
Range: ENABLE , DISABLE P.314 = (1$%/(
Range: 75% to 150% P.313 =