Motor - Stability Tab

Option Descriptions
Option	Description
Enable Motor Model	Select the check box to enter stability information. Without this, you cannot run a dynamic simulation for the motor.
Motors
Mfr	Provides a list of manufacturers available in the device library. If the desired manufacturer is not listed in the device library, you can add it to the library.
Type	Equipment types available from the selected manufacturer. If the desired type is not listed, you can add it to the library.
Lib	Populates the table with equipment data from the library. See EasyPower Device Library for more information.
Model	Equipment models available from the selected equipment type. If the desired model is not listed, you can add it to the library.
Define Parameters	Enables you to obtain an estimate of the motor circuit parameters from the torque vs. speed characteristics. See Define Motor Parameters .
Starting	This setting selects the method by which the motor will be initialized. The two options for this setting are: Init Using Rated Power: When initialized using rated power (default), the motor determines the slip necessary to maintain the terminal power conditions (kW) from the power flow case. Motor kVar is determined completely by the induction motor machine equations. Init Using Rated Slip: When initialized using rated slip, the motor forces terminal real power conditions (kW) to correspond to the specified rated slip of the motor. Thus, power conditions defined in the power flow case are abandoned to match slip. Motor kVar is determined completely by the induction motor machine equations. Explanation: There are conditions where a motor parameter derivation has significant errors in rated conditions (such as upwards to 10%) when attempting to match a manufacturer's torque vs. speed curve. This is most likely created by inconsistencies in the supplied data for various reasons. For such conditions, initializing to rated power defined by the power flow causes a new slip to manifest through initialization, which is not equal to the specified rated slip. This then creates a condition where the torque produced by the motor during starting can be significantly greater than the torque vs. speed curve generated in the parameter derivation. For a motor in a borderline start condition (near stalling), the results may show an incorrect successful start (we have seen up to 12% greater torque over the motor's speed range). To correct for this, select "Init Using Rated Slip". This will force the motor to re-create the exact torque vs. speed curve generated in the parameter derivation. Note however that the rated conditions reached after starting will have the error accepted in the parameter derivation.
Motor Starting Load This section defines the model for load characteristics while the motor is starting.
Mfr	Provides a list of starting load characteristics available in the device library.
Type	Starting load types available from the manufacturer selected in the Mfr field above.
Model	Lists available starting load models in the library. The choices are: Speed Squared: The torque is proportional to the square of the speed. Speed Cubed: The torque is proportional to the cube of the speed. Torque vs. Speed: User-defined spreadsheet.
Lib	Populates the table with equipment data from the library. See EasyPower Device Library for more information.
Motor Running Load This section defines the model for load characteristics while the motor is running.
Mfr	Provides a list of manufacturers available in the device library. If the desired manufacturer is not listed in the device library, you can add it to the library.
Type	Equipment types available from the selected manufacturer. If the desired type is not listed, you can add it to the library.
Model	Equipment models available from the selected equipment type. If the desired model is not listed, you can add it to the library.
Lib	Populates the table with equipment data from the library. See EasyPower Device Library for more information. You can also use the Define Motor Parameters feature described below to derive the motor parameters.

Enable Motor Model

Select the check box to enter stability information.

Without this, you cannot run a dynamic simulation for the motor.

Motors

Mfr

Provides a list of manufacturers available in the device library. If the desired manufacturer is not listed in the device library, you can add it to the library.

Type

Equipment types available from the selected manufacturer. If the desired type is not listed, you can add it to the library.

Lib

Populates the table with equipment data from the library. See EasyPower Device Library for more information.

Model

Equipment models available from the selected equipment type. If the desired model is not listed, you can add it to the library.

Define Parameters

Enables you to obtain an estimate of the motor circuit parameters from the torque vs. speed characteristics. See Define Motor Parameters .

Starting

This setting selects the method by which the motor will be initialized. The two options for this setting are:

Init Using Rated Power: When initialized using rated power (default), the motor determines the slip necessary to maintain the terminal power conditions (kW) from the power flow case. Motor kVar is determined completely by the induction motor machine equations.
Init Using Rated Slip: When initialized using rated slip, the motor forces terminal real power conditions (kW) to correspond to the specified rated slip of the motor. Thus, power conditions defined in the power flow case are abandoned to match slip. Motor kVar is determined completely by the induction motor machine equations.

Explanation: There are conditions where a motor parameter derivation has significant errors in rated conditions (such as upwards to 10%) when attempting to match a manufacturer's torque vs. speed curve. This is most likely created by inconsistencies in the supplied data for various reasons. For such conditions, initializing to rated power defined by the power flow causes a new slip to manifest through initialization, which is not equal to the specified rated slip. This then creates a condition where the torque produced by the motor during starting can be significantly greater than the torque vs. speed curve generated in the parameter derivation. For a motor in a borderline start condition (near stalling), the results may show an incorrect successful start (we have seen up to 12% greater torque over the motor's speed range). To correct for this, select "Init Using Rated Slip". This will force the motor to re-create the exact torque vs. speed curve generated in the parameter derivation. Note however that the rated conditions reached after starting will have the error accepted in the parameter derivation.

Motor Starting Load

This section defines the model for load characteristics while the motor is starting.

Mfr

Provides a list of starting load characteristics available in the device library.

Type

Starting load types available from the manufacturer selected in the Mfr field above.

Model

Lists available starting load models in the library. The choices are:

Speed Squared: The torque is proportional to the square of the speed.
Speed Cubed: The torque is proportional to the cube of the speed.
Torque vs. Speed: User-defined spreadsheet.

Lib

Populates the table with equipment data from the library. See EasyPower Device Library for more information.

Motor Running Load

This section defines the model for load characteristics while the motor is running.

Mfr

Provides a list of manufacturers available in the device library. If the desired manufacturer is not listed in the device library, you can add it to the library.

Type

Equipment types available from the selected manufacturer. If the desired type is not listed, you can add it to the library.

Model

Equipment models available from the selected equipment type. If the desired model is not listed, you can add it to the library.

Lib

Populates the table with equipment data from the library. See EasyPower Device Library for more information.

You can also use the Define Motor Parameters feature described below to derive the motor parameters.

Motor - Stability Tab

More Information