Motor Properties

Use Motor Properties to calculate Voltage Flicker. This calculation determines the amount that voltage briefly fluctuates when a motor (such as an air conditioner) is started.

You must add motors to the circuit manually, since the standard AM/FM data model does not have a motor entity. Right click the transformer entry in the Secondary Circuit Analysis window and select Add > Motor.

The % Voltage Flicker field is the percentage of flicker at the motor location when the motor is started. Enter the horsepower of the motor, its National Electrical Manufacturers Association (NEMA) motor code, and select 3-phase or 1-phase to calculate the amount of flicker. If the transformer at the head of the circuit is 1-phase, the 3-phase option button on the Motor Properties dialog is disabled. The impedance of the circuit to the motor, as well as the motor's starting inrush kVA, are also computed and displayed.

You may use the HP/NEMA Worksheet to determine the maximum size motor (HP) for a given NEMA rating, or the minimum NEMA rating for a given HP, that can be started and still remain within a specified flicker limit. Enter the Max Allowable Flicker first, then use the Compute HP or the Compute NEMA option to indicate which of the two quantities is to be optimized while the other is held constant. Enter the quantity to be held constant, and click Apply to recompute the other quantity (its field will be shown with a gray background to indicate that it is a computed value).

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