Technical information

8 – THEORY OF OPERATION
Deceleration Control
128
8.4.2 TruTorque Deceleration
Overview
TruTorque deceleration control is a closed loop deceleration control. This allows TruTorque
deceleration to be more consistent in cases of changing line voltage levels and varying motor load
conditions. TruTorque deceleration is best suited to pumping and compressor applications where
pressure surges, such as water hammer, must be eliminated. The MX linearly reduces the motor’s
torque to smoothly decelerate the motor and load. TruTorque deceleration is very easy to use with
only two parameters to set.
Figure 24 – TruTorque Deceleration
Motor
Torque
Time
Decel Time
End Torque
Level
Stop command
Motor Torque
Before Stop
Command
Beginning Level TruTorque deceleration control automatically calculates the motor loading when the stop command
was given and uses this value as the beginning level for the TruTorque deceleration ramp. Therefore
there is no parameter to set and the calculated beginning torque value provides a very smooth
transition from running to deceleration.
Ending Level The Decel End Level parameter sets the ending torque level for the TruTorque deceleration ramp
profile.
A typical TruTorque decel end level setting is between 10% and 20%. If the motor stops rotating
before the deceleration time has expired, increase this parameter value. If the motor is still rotating
when the deceleration time has expired, decrease this parameter value.
Decel Time The decel time sets the ramp time between the motor torque level when stop was commanded and the
decel end torque level.
If the motor stops rotating before the decel time has expired, decrease the decel time parameter. If
the motor is still rotating when the decel time expires, increase the decel time parameter.