Rockwell Automation SA3100 Distributed Power System Drv Config,Program - Manual (Page 143)

Torque Overload Ratio Parameter Precautions G-1
A
PPENDIX
G
Torque Overload Ratio
Parameter Precautions
The maximum RMS current that will be generated by the Power Module based on the
entered Torque Overload Ratio must be within the limits of the selected Power Module
or a warning will be generated:
* Power Module Rated Amps for the selected Power Module.
In some cases, however, the internal limit checking rules may be too conservative and
generate a warning even when the Power Module Rated Current and Torque
Overload Ratio values are consistent. It is not unusual for an application to
momentarily exceed the continuous full load current rating of the Power Module, e.g.,
150% for one minute.
When the Power Module continuous current rating is exceeded, it is the responsibility
of the application programmer to ensure that the maximum Power Module RMS
current rating is not exceeded. The above warning provides a flag to the user to check
that the proper application programs are in place to protect the Power Module by not
exceeding the maximum Power Module ratings.
The data entered by the programmer is checked by multiplying the Motor Full Load
Current by the specified Torque Overload Ratio. If the resulting current exceeds the
current rating of the Power Module, the warning is displayed. The checking algorithm
assumes that motor current and torque are proportional, although this may not be
completely accurate.
Internal limit checking for this parameter cannot be performed more accurately
because the magnetizing component of the current (Iz) is not available until tuning is
enabled in the PMI Regulator. Tuning, in turn, cannot be performed until the
parameter object file and UDC task have been loaded to the UDC.
In order to determine if it is permissible to proceed with the application data entry
when the warning appears, a more accurate approximation of the maximum RMS
current that is required for a specific Torque Overload Ratio level may be obtained by
applying the following equation for the current vector magnitudes:
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