Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 67)

PARAMETER AND VARIABLE DESCRIPTIONS 6-11
1557-UM050F-EN-P – June 2013
Ramp Test Step [Ramp test step]
Linear number:
80
Minimum value: 0.0 Hz
Maximum value: 30.0 Hz
Default value: 0.0 Hz
This parameter specifies the magnitude of the step that is added to the speed command to demonstrate the
response of the speed ramp. If this parameter is set to a non zero value, the drive will continuously ramp up
and down between a maximum speed equal to the speed command plus the value of this parameter, and a
minimum value equal to the speed command minus the value of this parameter. The ramp test function is
intended to be used in factory test only. This parameter is not saved and is initialized to zero at power up.
6 Speed Control Parameters
Speed Regulator Bandwidth [Spdreg bandwidth]
Linear number:
81
Minimum value: 0.5 r/s
Maximum value: 5.0 r/s
Default value: 1.0 r/s
This parameter specifies the small signal bandwidth of the speed control loop. It is used in the calculation of
the speed regulator gains. This parameter affects only the response time of the speed regulator and not the
overshoot. The speed regulator bandwidth will automatically be reduced to limit the bandwidth-inertia product
to a maximum of 30.
Total inertia [Total inertia]
Linear number:
82
Minimum value: 0.10 sec
Maximum value: 100.00 sec
Default value: 1.00 sec
This parameter specifies the total inertia of the motor and load, which is defined as the time required to
accelerate to rated speed at rated torque. This parameter replaces the mechanical time constant parameter
used in firmware revisions prior to 4.00. When upgrading the firmware, either the speed regulator should be
retuned or the inertia can be calculated using the following relationship between the old and new parameters:
Total inertia = 1.47 X T mechanical
2
Torque Rate Limit [Trq rate limit]
Linear number:
83
Minimum value: 0.00
Maximum value: 60.00
Default value: 10.00
This parameter specifies the maximum change allowed in the torque command in one second. The purpose of
this parameter is to prevent rapid changes in motor torque that might damage shafts and couplings. A value of
1.00 corresponds to rated motor torque in one second. Setting the torque rate limit too low will cause the
speed regulator to overshoot.
Prior to Rev 4.60/5.00, this parameter was scaled in per unit per cycle and was a much smaller number.
Torque Limit Motoring [Trq lmt motoring]
Linear number:
84
Minimum value: 0.00
Maximum value: 1.50
Default value: 1.00
This parameter specifies the maximum value of the torque command when motoring. A value of 1.00
corresponds to rated motor torque.
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.