Technical information

8 – THEORY OF OPERATION
Deceleration Control
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8.4 Deceleration Control
8.4.1 Voltage Control Deceleration
Overview
The deceleration control on the MX uses an open loop voltage ramp. The MX ramps the voltage
down to decelerate the motor. The curve shows the motor voltage versus the decel setting.
Figure 23 – Motor Voltage Versus Decel Level
Beginning Level This sets the starting voltage of the deceleration ramp. Most motors require the voltage to drop to
around 60% or lower before any significant deceleration is observed. Therefore, a good first setting
for this parameter is 35%.
To adjust this parameter, it is necessary to observe the motor operation as soon as a stop is
commanded. If the motor hunts (speed oscillations) at the beginning of the deceleration, then lower
the parameter by 5%. If the motor has a big drop in speed as soon as a stop is commanded, then raise
the parameter by 5%.
Some motors are very sensitive to the adjustment of this parameter. If a 5% adjustment changes the
motor from hunting to dropping in speed, then a smaller change of 1% or 2% may be necessary.
Ending Level This sets the final voltage for the deceleration ramp. In most cases, this parameter can be set to 10%
and the decel time can be used to adjust the deceleration rate. If the motor is coming to a stop too
quickly or if the starter continues to apply current to the motor after the motor has stopped, this
parameter can be increased in 5% increments to fix this.
Decel Time The decel time sets how quickly the motor decelerates. Usually a time of 30 seconds is a good
starting point. To make the motor take longer to decelerate, increase this parameter or to make the
motor decelerate quicker, decrease this parameter.
Note: Deceleration control provides a smoother stop. However, the motor will take longer to stop
than if it was just allowed to coast to stop.