Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 226)

9-26 COMMISSIONING
1557-UM050F-EN-P – June 2013
Tuning Procedure
The Bulletin 1557 medium voltage drive must be tuned to the motor and load to which it is connected. There
are six drive functions that require tuning. These are listed below in the order in which they are usually
performed:
Commutation Inductance Autotune Select = 1
Current Regulator Autotune Select = 2
Motor stator resistance Autotune Select = 4
Motor leakage inductance Autotune Select = 5
Flux Regulator Autotune Select = 6
Speed Regulator Autotune Select = 7
The first four functions can be tuned with the motor stationary, but the tuning of the flux and speed regulators
requires the motor to rotate.
1. Commutation Inductance
The commutation inductance is used in the hardware reconstruction of the line voltage to compensate for
commutation notches. It is also used in the calculation of the line converter retard limit to ensure proper
operation under all conditions of line voltage and load current when regenerating. If the commutation
inductance parameter is not correctly adjusted, the resulting distortion in the reconstructed line voltage may
cause line synchronization faults.
The commutation inductance parameter is tuned with the drive operating in the dc current test mode. Although
the commutation inductance was tuned during factory test, it must be retuned during commissioning because
its value is determined by the impedance of the input transformer and harmonic filter (if present). The following
autotune procedure can be used:
Commutation Inductance Autotuning
1.
Set parameter "Autotune select" in "P Autotune" to 1. The drive will go into dc current test mode.
2.
Start the drive. The dc current will increase in steps up to approximately rated current in about 2 seconds.
When the current reaches its maximum value the drive shuts off.
Parameter "Autotune Lc" in "P Autotune" is set to the measured value of commutation inductance and parameter
"Autotune select" is set to zero. If the test is successful, parameter "L commutation" in "P Current Control" is set
equal to "Autotune Lc". If the test fails then parameter "L commutation" is not changed and a warning is issued
indicating the cause of the failure:
L comm low - indicates that the measured commutation inductance is less than 0.02 pu. The commutation
inductance must be tuned using the manual method described below.
L comm high - indicates that the measured commutation inductance is greater than 0.15 pu. The commutation
inductance must be tuned using the manual method described below.