24. NEMA-rated general-purpose motors can operate on voltages 610% of their rated nameplate voltage. An unbalanced voltage situation is extremely damaging to a motor. Calculate the expected heat rise in a motor subjected to an unbalanced voltage situation where the voltages between phases AB = 465 volts, BC = 487 volts, and CA = 473 volts. Add these voltages: Total Find the average voltage: Total ÷ 3 = volts Full Subtract the average voltage from the voltage reading that results in the greatest difference: volts 100 ÷ Greatest voltage difference/Average voltage = %voltage unbalance Temperature rise in the winding with highest current = 2 × (percent voltage unbalance)? % temperature rise in the winding with highest current

24. NEMA-rated general-purpose motors can operate on voltages 610% of their rated nameplate voltage. An unbalanced voltage situation is extremely damaging to a motor. Calculate the expected heat rise in a motor subjected to an unbalanced voltage situation where the voltages between phases AB = 465 volts, BC = 487 volts, and CA = 473 volts. Add these voltages: Total Find the average voltage: Total ÷ 3 = volts Full Subtract the average voltage from the voltage reading that results in the greatest difference: volts 100 ÷ Greatest voltage difference/Average voltage = %voltage unbalance Temperature rise in the winding with highest current = 2 × (percent voltage unbalance)? % temperature rise in the winding with highest current

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter34: Motor Installation

Section: Chapter Questions

Problem 6PP: A 350-HP squirrel-cage induction motor is connected to a 480-volts three-phase feeder. The nameplate...

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