Rockwell Automation 1397 Regulated Field Supply Card - Manual (Page 3)

1397 – 5.17 September, 1997
1397 Regulated Field Supply Card 3
As shown above, in the Constant Torque (armature control) range, the
Field Control Loop can be configured to decrease Armature Voltage
1
when the motor’s armature is greater than P.284 [Fld Weaken Level] and
the field begins to weaken. As motor speed increases beyond base
speed, Armature Voltage will increase above rated voltage. PI
(proportional plus integral) Block 2 monitors armature voltage and
will reduce the HI limit of PI Block 1 that controls field current. As
field current decreases, field flux and Armature Voltage also
decreases. Field current continues to decrease until Armature Voltage
is equal to the value set in
P.284 [Fld Weaken Level] .
1 The armature IR drop can be compensated for by resetting parameter P.066 [IR Compensation].
The field control loop can operate in one of two ranges — A
Constant Torque (armature control) Range or a Constant HP (field
control) Range.
If the Regulated Field Supply Card’s factory defaults are set, it will
operate in a fixed voltage mode by firing the field SCRs at a fixed
angle of 117°. This will produce a motor field voltage of 150V DC
with a 230V AC line input, or 300V DC with a 460V AC line input.
To produce other motor field voltages, parameter
P.044 [Motor Field
Amps] must be set as described in the Setup section of this
publication before motor startup. Even though the Regulated Field
Supply will be producing fixed voltage, the value of parameter
P.044
will be set to 0.01 Amps. After a valid value is entered for P.044 , the
user-assigned value for parameter P.277 [Fld Loss Level] becomes
effective.
Important: The Regulated Field Supply Card will not regulate field
current until a valid value for parameter
P.044 is entered. The drive
can be operated however, when the Regulated Field Supply Card is
operating in the fixed voltage mode. Field loss detection will only
occur if there is a complete loss of field current. This is similar to
having the Fixed or Enhanced Field Supply installed.
The Field Control Loop contains (2) regulators — A Field Current
Regulator and an Armature Voltage (or counter-EMF) Regulator.
How This Option Works
(continued)
CONSTANT HP CONSTANT TORQUE
BASE SPEED
100%
of FIELD CURRENT
or ARMATURE VOLTAGE
0%
of FIELD CURRENT
or ARMATURE VOLTAGE
FIELD CURRENT
ARMATURE VOLTAGE
ARMATURE VOLTAGE
TOP SPEED
FIE
LD
C
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R
R
EN
T
W
EA
KE
NIN
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