Motor - TCC Tab

Option Descriptions
Option	Description
Motor Starter Type	Provides a list of motor starters. Select the appropriate starter from the following: Full Voltage: The motor starts at the rated voltage, without any starting device connected to it. Auto-transformer: An auto-transformer is used as a starting device to reduce the starting current. The tap value of the auto-transformer, as a percentage of the rated motor voltage, is entered in the edit field Auto-Xfrmr Tap at the bottom of the dialog box. Part-Winding: Part-winding start motors, in which only a part of the winding is used for starting. The entire winding is energized after start up. The Winding Tap must be specified at the bottom of the dialog box. Wye-Delta: The starter keeps the motor windings in wye-connection while starting to reduce the starting current. After start up the starter connects the windings in delta configuration. Reduced Voltage: The starting voltage during starting is less than the rated voltage. The inrush current for reduced voltage starting, as a multiple of full load amps, must be specified at the bottom of the dialog box.
Largest	In grouped motor data, you can specify the size of the largest motor. This field is unavailable when you select the motor as individual motor. When you plot the motor starting curve on a time-current curve (TCC), the program plots the curve such that the largest motor is being started and the rest of the motors in the group are running at full load.
Full Voltage Starting Parameters This section specifies the motor current characteristics during starting at the rated motor voltage.
Locked Rotor Multiple	Locked rotor current as multiples of full load amps.
Asymmetrical (Asym) Offset	Factor by which the inrush current is higher due to the asymmetry current.
Plot Thermal Limit Curve	Check box to plot thermal limit time-current curve of the motor. The curve is shown within the limits of the Stall Time described below. The curve is an I²t curve passing through the Stall Time and the locked rotor amps.
Stall Time	The maximum time in seconds that the motor can safely withstand stalling.
To	The maximum time in seconds of the thermal limit curve of the motor you want to plot.
Reduced Voltage Starting Parameters	Specifies the starting time and the current or voltage ratio under reduced voltage. Depending upon the motor starter type selected enter one of the following. The starting current will be calculated from this. Auto-Xfrmr Tap: The auto-transformer tap ratio as a percentage of rated voltage. Winding Tap: Starter winding ratio as a percentage of full motor winding. Reduced Inrush Mult: The inrush current at reduced voltage, as a multiple of full load amps.
Acceleration Time	The starting time in seconds.
Conn. Auto-Scale	When this check box is selected, the program automatically scales the TCC curves based on the phase connection type. Traditionally, for 3PH curves in a TCC, scaling the curves based on the reference voltage is adequate. If a line-to-neutral connected 1PH device is to be plotted with an upstream 3PH device, then the LN connected 1PH curve needs to be shifted by a factor of the SQRT(3) in addition to the voltage-based scaling. Similarly, if a line-to-neutral connected 1PH device is to be plotted with an upstream 1PH-3W device, then the LN connected 1PH curve needs to be shifted by a factor of the 2 in addition to the voltage-based scaling.When the check box is not selected, scaling based on the phase connection type is not applied. The check box status for individually stored TCC plots can be different. The default for new TCC plots is obtained from the database for the device.

Motor Starter Type

Provides a list of motor starters. Select the appropriate starter from the following:

Full Voltage: The motor starts at the rated voltage, without any starting device connected to it.
Auto-transformer: An auto-transformer is used as a starting device to reduce the starting current. The tap value of the auto-transformer, as a percentage of the rated motor voltage, is entered in the edit field Auto-Xfrmr Tap at the bottom of the dialog box.
Part-Winding: Part-winding start motors, in which only a part of the winding is used for starting. The entire winding is energized after start up. The Winding Tap must be specified at the bottom of the dialog box.
Wye-Delta: The starter keeps the motor windings in wye-connection while starting to reduce the starting current. After start up the starter connects the windings in delta configuration.
Reduced Voltage: The starting voltage during starting is less than the rated voltage. The inrush current for reduced voltage starting, as a multiple of full load amps, must be specified at the bottom of the dialog box.

Largest

In grouped motor data, you can specify the size of the largest motor. This field is unavailable when you select the motor as individual motor. When you plot the motor starting curve on a time-current curve (TCC), the program plots the curve such that the largest motor is being started and the rest of the motors in the group are running at full load.

Full Voltage Starting Parameters

This section specifies the motor current characteristics during starting at the rated motor voltage.

Locked Rotor Multiple

Locked rotor current as multiples of full load amps.

Asymmetrical (Asym) Offset

Factor by which the inrush current is higher due to the asymmetry current.

Plot Thermal Limit Curve

Check box to plot thermal limit time-current curve of the motor. The curve is shown within the limits of the Stall Time described below. The curve is an I²t curve passing through the Stall Time and the locked rotor amps.

Stall Time

The maximum time in seconds that the motor can safely withstand stalling.

To

The maximum time in seconds of the thermal limit curve of the motor you want to plot.

Reduced Voltage Starting Parameters

Specifies the starting time and the current or voltage ratio under reduced voltage. Depending upon the motor starter type selected enter one of the following. The starting current will be calculated from this.

Auto-Xfrmr Tap: The auto-transformer tap ratio as a percentage of rated voltage.
Winding Tap: Starter winding ratio as a percentage of full motor winding.
Reduced Inrush Mult: The inrush current at reduced voltage, as a multiple of full load amps.

Acceleration Time

The starting time in seconds.

Conn. Auto-Scale

When this check box is selected, the program automatically scales the TCC curves based on the phase connection type. Traditionally, for 3PH curves in a TCC, scaling the curves based on the reference voltage is adequate. If a line-to-neutral connected 1PH device is to be plotted with an upstream 3PH device, then the LN connected 1PH curve needs to be shifted by a factor of the SQRT(3) in addition to the voltage-based scaling. Similarly, if a line-to-neutral connected 1PH device is to be plotted with an upstream 1PH-3W device, then the LN connected 1PH curve needs to be shifted by a factor of the 2 in addition to the voltage-based scaling.When the check box is not selected, scaling based on the phase connection type is not applied. The check box status for individually stored TCC plots can be different. The default for new TCC plots is obtained from the database for the device.

Motor - TCC Tab

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