Beck, R&J ELECTRIC ACTUATORS FOR INDUSTRIAL PROCESSCONTROL 11-1_9 Manual Do Utilizador

21

 

When the Demand input signal drops to 

approximately –5%, the DCM-2 considers the 
Demand input signal to be invalid.  DCM-2s are 
typically configured to stop the drive during L.O.S. 
conditions, but may be configured by the factory 
or by using the HART or Serial interface to run the 
drive to a predetermined position.  Under the L.O.S. 
condition, the “STAT” and “DEMAND” LEDs will 
light.  When the input signal is corrected, the drive 
will automatically resume normal operation.  The 
value for LOS activation is configurable using the 
HART (see page 47) or Serial interface (see page 
70).  Alarm indication is available at terminal E.

 

The CPS provides the DCM-2 with a continuous 

feedback signal proportional to the position of the 
drive’s output shaft.  
 

The position sensing function of the CPS is 

provided by a ferrite magnetic sensing element.  
An electronic circuit translates the signal from the 
ferrite magnetic sensor into a position signal used by 
the DCM-2 to control the drive.  The typical output 
voltage of the CPS ranges from 1.0 V at the CCW 
end of travel, to 5.0 V at the CW end of travel.  A 
4–20 mA position feedback signal is available for 
remote position indication (see page 17).  If the CPS 
Position signal to the DCM-2 is out of the calibrated 
range limits, the "STAT" and "POSITION" LEDs will 
light and the drive will not operate until the limits are 
adjusted or the CPS is corrected.  Alarm indication 
is available at terminal E. 

 

DCM-2s are equipped with a torque sensing 

module that will light the “STAT” and “TRQ/
THRUST” LEDs in the event excessive torque is 
detected.  This alarm is normally set to activate 
when torque exceeds 105% of the drive rating.  
Torques above 150% of the drive rating will cause 
the DCM-2 to stop trying to run in the direction of 
the high torque.  When the over torque condition 
is corrected, the drive will automatically resume 
normal operation.  The torque sensing module 
also provides a number of torque related features 
using the HART interface (see page 48).  Torque 
alarm may be enabled or disabled using the 

HART (see page 48) or Serial interface (see page 
71).  Torque alarm levels may be adjusted using 
the HART or Serial interfaces.  Alarm indication is 
available at terminal E.

 

If the drive output shaft cannot reach a desired 

position within approximately 300 seconds, the 
DCM-2 shuts off power to the motor and the “STAT” 
and “STALL” LEDs will light.  The stall condition 
timing is factory configurable (or configurable using 
the HART or Serial interface) from 300 seconds to 
as low as 30 seconds and is initially set according 
to the specification at time of order.     
 

A sensed stall condition is cleared  by either 

reversing the Demand input signal from the 
controller (such that the drive tries to run in 
the direction opposite the blocked direction), 
performing a "Reset Stall" or "Board Reset" using 
the HART interface (see page 42), or by switching 
the drive power off and on. Alarm indication is 
available at terminal E.

 

DCM-2s are equipped with a temperature 

sensing circuit.  The “STAT” and “TEMP 
°F” LEDs will light when the drive’s ambient 
temperature exceeds the rating of the drive.  
Specific temperature readings are available using 
the HART (see page 40) or Serial (see page 
72) interface.  Alarm indication is available at 
terminal E.

 

The feedback sourcing module provides a 

4–20 mA analog output signal that represents the 
drive output shaft position in terms of 0–100% of 
full rotational travel (configurable via the HART 
(see page 56) or Serial (see page 75) interface).  
This signal can be remotely monitored or used 
by a controller or indicator.  The “STAT” and “FB 
OPEN” LEDs will light if the function is enabled 
and there is no current in the loop.  The Feedback 
signal can be factory configured as disabled, or 
disabled using the HART (see page 46) or Serial 
(see page 71) interface.  Alarm indication is 
available at terminal E.

 

The “STAT” and “STOP/LIMIT” LEDs will 

light if the Handswitch is in the “STOP” position.  
These LEDs will also light if the drive is at a 
limit and is not in balance.  Alarm indication is 
available at terminal E.