Mathcad - 09-05

Mathcad - 09-05 - ⋅ = f rated 60 Hz ⋅ = a Assuming...

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so the operating speed is 1440 rpm rpm n s25 1.5 10 3 × = n s25 120 25 2 = At 60 hz, the motor runs a 3560 rpm at full load indicating 40 rpm of slip e. The approximate operating speed can be found by calculating the synchronous speed at 25 hz and then subtracting the slip speed HP 85hz 100hp = HP 85hz HP rated = d. Above rated frequency, we are in the constant hp regime so HP 25hz 41.667hp = HP 25hz f 25 f rated HP rated = c. Rated hp at 25 hz, will be proportional to frequency so V 85hz 460V = V 85hz V rated = b. At 85 hz, only rated voltage would be applied to the motor we should apply 191.7 volts (line to line) to the motor V 25hz 191.667V = V 25hz f 25 f rated V rated = f 25 25 Hz
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Unformatted text preview: ⋅ = f rated 60 Hz ⋅ = a. Assuming volts per hertz control of the motor, the voltage must be reduced proportionally to the frequency when frequency drops below rated frequency Solution HP rated 100 hp ⋅ = V rated 460 V ⋅ = Problem 9-5 n rated 3560 rpm ⋅ = rpm 1 min ≡ f. The approximate operating speed can be found by calculating the synchronous speed at 85 hz and then subtracting the slip speed At 60 hz, the motor runs a 3560 rpm at full load indicating 40 rpm of slip n s85 120 85 ⋅ 2 = n s85 5.1 10 3 × = rpm so the operating speed is 5060 rpm...
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This note was uploaded on 03/26/2012 for the course ECET 231 taught by Professor Piller during the Spring '12 term at Purdue.

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Mathcad - 09-05 - ⋅ = f rated 60 Hz ⋅ = a Assuming...

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