Owner manual

Field Current Regulator Description A-1
APPENDIX A
Field Current Regulator Description
Description of the Field Control Loop
The FlexPak 3000 version 3 regulator will detect the presence of the Field Current
Regulator kit at power-up. The output parameter
FLD CURRENT REGULATOR indicates
whether or not the Field Current Regulator kit is in-stalled. When the Field Current
Regulator kit is installed, the field current control loop operates and drive parameters
ENHANCED FLD VOLT ADJ and J21 FLD SUPPLY JUMPER are ignored. The regulated field
loss and field economy circuits become active in place of those used by the standard
and enhanced field supplies. See figure A.1 for a block diagram of the field control
loop.
Important: The regulator board jumper J20 (
FIELD LOSS DETECT) is ignored when the
Field Current Regulator is in-stalled. Therefore, setting J20 to the
DISABLE position will NOT disable field loss detection.
The field control loop contains two regulators: a field current regulator and an
armature voltage (counter-EMF or CEMF) regulator. The field control loop can be
configured to decrease armature voltage when the armature voltage feedback
(
ARMATURE VOLTAGE) exceeds the FLD WEAKEN THRESHOLD voltage and the field begins
to weaken (see figures A.1 and A.2). The armature IR drop can be compensated for
by using the
IR COMPENSATION parameter (P.206).
The output of the Field Current Regulator determines the firing angle of the regulated
field supply gate firing circuit. The output parameter
FIELD DELTA represents the angle
in degrees. If the factory defaults for the Field Current Regulator are in effect, it will
operate in a fixed voltage mode by firing the field SCRs at a fixed angle of 117º. This
will produce a field voltage of 150 VDC at 230 VAC line input or 300 VDC at 460 VAC
line input. For other motor field voltages,
MOTOR HOT FLD AMPS must be set properly
before the motor field is connected. While the Field Current Regulator is producing
fixed voltage, the value for
MOTOR HOT FLD AMPS will be set to 0.01 amps. After a valid
value is entered for
MOTOR HOT FLD AMPS, the user-assigned value for FIELD LOSS
THRESHOLD becomes effective. The Field Current Regulator will NOT regulate field
current until a valid value for
MOTOR HOT FLD AMPS is entered. While in fixed voltage
mode, a field loss fault will only occur if there is a complete loss of field current. This is
similar to having a standard or enhanced field supply installed.
!
ATTENTION:If the factory defaults for the Field Current Regulator are
not in effect (e.g.,
MOTOR HOT FLD AMPS was modified via the network or
CS3000), extreme care must be exercised to ensure the correct value
for
MOTOR HOT FLD AMPS is present when power is applied to the drive.
Failure to observe this precaution could result in damage to, or
destruction of, the equipment.