Power - Thermal Mgmnt Config Attrib

These are the power and thermal configuration-related attributes associated with a Motion Control Axis.

Motor Overload Action

The Motor Overload Action attribute selects the device's response to a motor overload condition based on an I

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T or motor thermal model-based overload protection method. When a motor thermal model is employed, the motor overload condition occurs when the motor thermal model indicates that the Motor Capacity has exceeded the Motor Overload Limit. In the case of the I

2

T overload protection method, the motor overload condition occurs when the motor current, in percent of rated continuous motor current, exceeds the Motor Overload Limit. The Motor Overload Action provides opportunities to mitigate the overload condition without stopping operation.

Motor Overload Action functionality is independent of the motor overload exception action functionality.

No explicit action is taken by the device in the overload condition if None is the selected overload action. Selecting the Current Foldback action, however, results in a reduction of the motor current command in proportion to the percentage difference between Motor Capacity and the Motor Overload Limit, or in the case of the I

2

T overload protection method, in proportion to the difference between the motor current, in percent of rated continuous motor current, and the Motor Overload Limit.

Inverter Overload Action

The Inverter Overload Action attribute selects the device's response to an inverter overload condition based on an I

2

T or inverter thermal model-based overload protection method. When an inverter thermal model is employed, the inverter overload condition occurs when the inverter thermal model indicates that the Inverter Capacity has exceeded the Inverter Overload Limit. In the case of the I2T ov

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rload protection method, the inverter overload condition occurs when the inverter current, in percent of rated continuous inverter current, exceeds the Inverter Overload Limit.

The Inverter Overload Action provides opportunities to mitigate the overload condition without stopping operation.

Inverter Overload Action functionality is independent of the inverter overload exception action functionality.

An overload alarm condition can also be generated by exceeding the limits of the device’s power block thermal model that includes switching losses that have a dependency on the PWM Frequency.

No explicit action is taken by the device in the overload condition if None is the selected overload action. Selecting the Current Foldback action, however, results in a reduction of the inverter current in proportion to the percentage difference between the Inverter Capacity and the Inverter Overload Limit, or in the case of the I2

T

overload protection method, in proportion to the difference between the inverter current, in percent of rated continuous inverter current, and the Inverter Overload Limit.

If an inverter overload condition occurs due to the power block thermal model, two additional overload actions can be applied. Selecting Reduce PWM Rate can be used to reduce heat generated by switching losses in the inverter power structure. When PWM –Foldback is selected the device first reduces the PWM rate and then, if necessary, reduces the Inverter Thermal Current Limit.