Please explain A 3-phase, 60Hz induction motor is used for a ski lift. It draws
ID: 2293084 • Letter: P
Question
Please explain
A 3-phase, 60Hz induction motor is used for a ski lift. It draws 150kVA at a power factor of 0.7 lagging with 460V (L-L). The motor is at the top of the mountain; therefore to cut costs the gauge of the wire should be minimal. An ENT-371 student came up with an idea to parallel a synchronous motor with the induction motor to lower the current, thus a smaller diameter cable could be used. The student also stated that the mechanical power from the synchronous motor could run the turbine in a large snow-making gun. The snow-making gun requires 12.8687 hp to run its turbine properly. The synchronous motor has an efficiency of 80%. The synchronous motor is overexcited so with the combination of motors the power factor on the line is 1.0.Explanation / Answer
Guage of wire inceases the cost of the system. poor power factor means high current and induction motor run at poor power factor. If we install synchronous motor in parallel to induction motor then synchronous motor will act as synchronos capacitor when it runs on overexcitation.Synchronous capacitor has leading power factor so it will compensate induction motor power factor to 1. And the power generated by the synchronous can also be used anywehere. Here the generated mechanical power is used on snow making gun. Because of high efficiency it can run large turbines.