Control Techniques Digitax ST Advanced User's Manual page 36

Parameter
Menu 2
structure
2.01 Post ramp reference
Bit SP
Coding
Range ±SPEED_FREQ_MAX rpm
Update rate 4ms write
2.02 Ramp enable
Bit SP
Coding
1
Default 1
Update rate 4ms read
2.03 Ramp hold
Bit SP
Coding
1
Default 0
Update rate 4ms read
If this bit is set the ramp will be held. If S ramp is enabled the acceleration will ramp towards zero causing the ramp output to curve towards a constant
speed. If a drive stop is demanded the ramp hold function is disabled.
2.04 Ramp mode select
Bit SP
Coding
Range 0 to 1
Default 1
Update rate 4ms read
This parameter does not affect the acceleration ramp, and the ramp output always rises at the programmed acceleration rate subject to the current
limits. If the drive attempts to stop the motor with an overhauling load, the motor will not stop when standard ramp mode or fast ramp mode is used. If
the drive is in the deceleration state the rate of fall of the speed is monitored. If this does not fall for 10 seconds the drive forces the speed reference
to zero. This only applies when the drive is in the deceleration state and not when the reference is simply set to zero. If the speed reference is just set
to zero with an overhauling or very high inertia load, then the drive may not decelerate.
0: Fast ramp
Fast ramp is used where the deceleration follows the programmed deceleration rate subject to current limits.
1: Standard ramp
Standard ramp is used during deceleration if the voltage rises to the standard ramp level (Pr 2.08). It causes a controller to operate, the output of
which changes the demanded load current in the motor. As the controller regulates the DC bus voltage, the motor deceleration increases as the
speed approaches zero speed. When the motor deceleration rate reaches the programmed deceleration rate the controller ceases to operate and the
drive continues to decelerate at the programmed rate. If the standard ramp voltage (Pr 2.08) is set lower than the nominal DC bus level the drive will
not decelerate the motor, but it will coast to rest. The output of the ramp controller (when active) is a current demand that is fed to the torque
producing current controller. The gain of these controllers can be modified with Pr 4.13 and Pr 4.14.
Controller
operational
Motor Speed
Programmed
deceleration
rate
36
Keypad and
Parameter x.00
display
FI DE Txt VM DP ND RA NC NV
1 1 1
FI DE Txt VM DP ND RA NC NV
FI DE Txt VM DP ND RA NC NV
FI DE Txt VM DP ND RA NC NV
1
DC Bus voltage
t
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Parameter Advanced parameter
description format descriptions
PT US RW BU
1 1
PT US RW BU
1 1
PT US RW BU
1 1
PT US RW BU
1 1
Serial comms Electronic
protocol nameplate
PS
PS
1
PS
PS
1
Digitax ST Advanced User Guide
Issue Number: 1
Performance