Hamilton Sundstrand Company ACT2000 - Manual (Page 42)

36 ACT2000 USER GUIDE
3.5 Controlling Motion
Once the Home position has been established, the DEMAND current
determines subsequent positioning of the actuator within its span. The
actuator will track the DEMAND signal as long as DEMAND ≥ 4.1 mA and
RUN is ON, and will apply up to the maximum force to reach this
DEMAND position. This is defined as the RUN state, and it is the normal
operating mode for the ACT2000.
The actuator firmware program will remain in this state as long as the
demand is greater than 4.1 mA.
Note: If RUN command is removed or position DEMAND ≤ 2 mA,
the actuator will go to the STOP position.
Home Position
The Home position correlates to a DEMAND signal of 4 mA. The Home
position is determined after Power Up or after the ACT2000 has been
reset.
Dead Band
While the Home position correlates to a DEMAND signal of 4 mA, the
actuator will only move for DEMAND signals ≥ 4.1 mA. The DEMAND
signal range between 4.0 mA and 4.1 mA is therefore considered a Dead
Band. See Figure 3-3.
Once a DEMAND signal ≥ 4.1 mA is detected, the actuator will move to
the position that correlates to that current level. See Interpolation of
DEMAND Signal below.
Hysteresis Band
The actuator should return to the Home position when the DEMAND
Signal drops below the 4.1 mA Dead Band threshold. In practice,
hysteresis may result in the actuator not returning to Home position until
the DEMAND signal drops below a threshold as low as 4.08 mA. The
DEMAND signal range between 4.08 mA and 4.1 mA is therefore
considered the Hysteresis Band. See Figure 3-3.
Full Span Position
The Full Span position correlates to a DEMAND signal of 20 mA. The
Span is specified in the Set Up parameters and has a default value of
5.9 inches of extension. (The default definition of Home is Retract, so
default Span is an extension.) The maximum Span possible for the
ACT2000 actuator is 5.9 inches due to its mechanical configuration.