BENSHAW RediStart EXEXMVRMX3 Series, User Manual

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Deceleration Control
7.4 Deceleration Control
7.4.1 Voltage Control Deceleration
Overview The deceleration control on the MX
3
uses an open loop voltage ramp. The MX
3
ramps the voltage down to
decelerate the motor. The curve shows the motor voltage versus the decel setting.
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.
z
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.
131
7 - THEORY OF OPERATION
Figure 38: Motor Voltage Versus Decel Level