80-4280-10, Rev. 4
CONFIGURATION / CALIBRATION
36
TORQUE SENSING
Group 22 actuators are equipped with torque
sensing. This technology allows for torque
measurement, historic data collection, overtorque
alarms, and overtorque protection.
The torque applied at the output shaft of
the actuator is measured and reported as a
percentage of the rated actuator torque (e.g. a
3,000 lb-ft model 22-309 with a 50% torque reading
is applying 1,500 lb-ft of torque). The live torque
measurement can be accessed through HART
communications (MENU 1) or serial port (torq
command). Historical peak measurements are
recorded for 10 equal segments of travel in both
the CW and CCW travel directions. This historic
data is available through HART communications
(MENU 11) or serial port (torqprof command).
Proper configuration of the torque sensor is
necessary to take advantage of its features. A
“torque null” and a “torque constant” value, which
are analogous to a zero and a span are unique
to each actuator and will be affixed to the body of
the unit inside of the DCM compartment. These
values will be factory configured on the DCM-2,
but will require configuration if the DCM-2 is ever
replaced.
When the torque reaches an alarm threshold
(factory configured for 105%), a status alarm will
be initiated causing the STAT and TORQUE LEDs
to illuminate. The threshold can be configured
to alarm between 60% and 105%. Disabling the
torque sensor also disables the torque alarm.
When the measured torque drops below the
threshold the status alarm is automatically reset.
The following methods allow the user to
enable/disable torque sensing, set the torque null,
set the torque constant, and set the torque alarm
threshold.
HART
method
HART DD Menu Location: MENU 5E
Functions> Configuration> Torque Setup
Command: Trq/Thrust
Selections:
Enabled -
Select to enable torque sensing.
Disabled -
Select to disable torque sensing.
Command: Trq Null
Enter the torque null value that is affixed to the
actuator body inside the DCM compartment.
Command: Trq Constant
Enter the torque constant value that is affixed to
the actuator body inside the DCM compartment.
Command: Alarm Level
Enter the torque alarm threshold as a percentage
of rated actuator torque (60%-105%).
SERIAL
command method
Command: torqenable
Arguments:
0:
Disable torque sensing and torque alarm.
1:
Enable torque sensing and torque alarm.
(e.g.: “torqenable 1” enables torque sensing and
torque alarm)
Command: torqzero
Arguments: ###:
Enter the torque null as an
integer that is affixed to the actuator body inside
the DCM compartment.
Command: torqspan
Arguments: ###:
Enter the torque constant as an
integer that is affixed to the actuator body inside
the DCM compartment.
Command: torqalarm
Arguments: ###:
Enter the torque alarm
threshold as a percentage of rated actuator torque
(60%-105%).
OVERTORQUE PROTECTION
Overtorque protection is a feature of the
actuator that is intended to protect both the
actuator and driven equipment from damage
when the torque level exceeds a certain threshold
by cutting power to the motor. Unless otherwise
specified at the time of order, this feature is
disabled as a factory setting. It can be enabled
in the field using either HART or serial command
methods. The factory configured threshold is
115% of rated actuator torque.
The following methods show how to enable/
disable the overtorque protection and how to set
the threshold which has an acceptable range
between 70% and 115%.
HART
method
HART DD Menu Location: MENU 5E
Functions> Configuration> Torque Setup
Command: Ovt Prot
Selections:
Enabled -
Enables Over torque protection.
Disabled -
Disables Over torque protection.
Command: ShutDwnTrq
Enter the over torque protection threshold as a
percentage of rated actuator torque (70%-115%).
