Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 70)

6-14 PARAMETER AND VARIABLE DESCRIPTIONS
1557-UM050F-EN-P – June 2013
Torque Command Minimum [Trq command min]
Linear number:
92
Minimum value: 0.00
Maximum value: 1.50
Default value: 1.50
This parameter specifies the minimum initial value of the torque reference when the speed regulator is enabled.
When starting a drive without tach feedback, the actual motor torque is measured and the torque reference is
set to an appropriate value before enabling the speed regulator. This is intended to reduce the speed
overshoot that can occur when Torque Command 1 is set too high. A value of 1.00 corresponds to rated motor
torque. This parameter has no effect when tach feedback is enabled.
The default setting disables this load dependent initialization of the torque reference. If this starting torque
adjustment function is required, “Torque Command Minimum” should be set to a value lower than “Torque
Command 1”.
Prior to Rev 4.60/5.00, this parameter was scaled in per unit based on the motor rated kVA and was about 10%
lower.
Speed Error Deadband [Spd err deadband]
Linear number:
93
Minimum value: 0.0 Hz
Maximum value: 5.0 Hz
Default value: 0.0 Hz
This parameter specifies a deadband for the speed regulator error. If the absolute value of the speed error is
less than the value of this parameter, the output of the speed regulator will not change. This parameter is
intended to be used only in torque control mode 5, and should be left at its default value of zero in all other
torque control modes.
Speed Feedback Filter [Spd fdbk filter]
Linear number:
110
Minimum value: 0 r/s
Maximum value: 50 r/s
Default value: 0 r/s
This parameter specifies the bandwidth of a second order low pass filter for the motor speed feedback. The
purpose of this filter is to attenuate any undesirable components, such as mechanical resonant frequencies, in
the speed feedback. Normally, this parameter should be left at its default value of zero, which automatically
selects a filter bandwidth equal to ten times the speed regulator bandwidth. At this setting, the filter will have
no noticeable affect on the response of the speed regulator, but as the filter bandwidth decreases below this
value, the speed regulator becomes more underdamped until it eventually becomes unstable.
This parameter was added in Rev 4.60/5.10.
Torque Rate Limit 0 [Trq rate limit 0]
Linear number:
111
Minimum value: 0.00
Maximum value: 60.00
Default value: 1.00
This parameter specifies the maximum change allowed in the torque command in one second during open loop
starting. The purpose of this parameter is to allow torque to be applied slowly when starting to avoid exciting
the torsional natural frequency of the mechanical system. This parameter is used only during open loop
starting. The normal Torque Rate Limit parameter is used when running and when starting with the optional
tach feedback enabled.
This parameter was added in Rev 4.72/5.20