Rockwell Automation FlexPak 3000 Drive Field Current Regulator Kit, 911FK0041, 911FK0101, 911FK015 - Manual (Page 38)

A-2 FlexPak 3000 Field Current Regulator Installation Instructions
Both field loop regulators contain proportional plus integral (PI) control. There is no
user-configurable low limit parameter associated with these PI blocks. The low limit is
always fixed at zero. The high limit (
FIELD DELTA HI LIM ) is user-configurable up to 180
degrees, allowing full-on field voltage of 207 VDC @ 230 VAC and 414 VDC @ 460
VAC. To regulate greater field voltages, a step-up transformer must be used to supply
the AC side of the Field Current Regulator.
As the motor speed increases beyond base speed, the armature voltage will increase
above rated voltage. The PI block monitoring armature voltage will reduce the high
limit of the PI block controlling field current. As field current decreases, field flux and
armature voltage will also decrease. Field current continues to decrease until
armature volt-age is reduced to
FLD WEAKEN THRESHOLD volts. Control of armature
voltage during field weakening is only permitted when a tachometer is used ( FEEDBACK
SELECT
≠
ARMATURE VOLTS ). Automatic field weakening can be disabled by setting
FIELD AUTO WEAKEN = DISABLED . The drive can also be operated in the constant power
(field control) range by controlling the field current reference exclusively ( FIELD REF
REGISTER ).