CONTREX CX-1200 - Manual (Page 131)

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RUN RAMPS
Since the ramp generator controls the rate of change of the velocity command, the velocity command is
referred to as the ramped reference speed. The ramped reference speed is displayed in RampedRef (MP-
31). When the ScaledRef (MP-30) speed changes, the rate of change in the RampedRef (MP-31) speed is
limited by the acceleration and deceleration rates that you specify. You can specify the rates for “Run”, “R-
Stop”, “H-Stop”, "Direct" and “Jog” independently.
Ramps may be used in each of the following situations:
1. The application requires slow starting and stopping to prevent product damage.
2. Minimize stress on your system during starting and stopping.
3. Minimize the overshoot of the response to step changes in the ScaledRef (MP-30).
4. Filter out high frequency components of the ScaledRef (MP-30) signal.
5. Keep the drive out of current limit (saturation) and thus maintain the linear properties of the
drive. The control loop will perform better and operate more predictably.
Your drive's capacity should not be exceeded under normal operating loads. If you use acceleration rates in
excess of your drive’s potential, then overshoot can occur. However, if the Lead in follower applications
provides adequate ramps, you can set the Acl Tm RUN (CP-301) or Dcl Tm RUN (CP-303) to “0.5”or use
Ramp Thd (CP-305). The Ramp Thd (CP-305) allows the ramp for large changes in the ScaledRef (MP-30)
and bypasses the ramp for small or gradual changes. The ramp generator can be stopped in progress or
bypassed through the PLC or by Cntrl Latch (CP-477).
Set the acceleration rate for the ramps by defining a reference speed for the ramps in Ref Ramps (CP-300).
The acceleration rate can also be entered directly in Acl Rt RUN (CP-302), although you must also enter a
valid reference speed in Ref Ramps (CP-300). This reference speed is generally the operating line speed.
When you enter an acceleration time in Acl Tm RUN (CP-301), the CX-1200 automatically calculates the
acceleration rate. Inversely, if you enter the acceleration rate in Acl Rt RUN (CP-302), the CX-1200
automatically calculates the acceleration time. The deceleration time and deceleration rate operate in the
same way. When you enter a new reference speed, the CX-1200 automatically calculates the acceleration
and deceleration times and preserves the given rates. The acceleration rate is defined by:
acceleration rate = reference speed (EU/Tm)
acceleration time (Seconds)
Likewise, the deceleration rate is defined by:
deceleration rate = reference speed (EU/Tm)
deceleration time (Seconds)