A 3-phase, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill between the slip-rings on open-circuit. Calculate the current and power factor at standstill when the rotor winding is joined to a star-connected external circuit, each phase of which has a resistance of 10 2 and an inductance of 0.04 H. The resistance per phase of the rotor winding is 0.2 2 and its inductance is 0.04 H. Also, calculate the current and power factor when the slip-rings are short-circuited and the motor is running with a slip of 5 per cent. Assume the flux to remain constant. [10.67 A; 0.376; 21.95 A; 0.303]

Understanding Motor Controls
4th Edition
ISBN:9781337798686
Author:Stephen L. Herman
Publisher:Stephen L. Herman
Chapter37: Motor Installation
Section: Chapter Questions
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มอเตอร์เหนี่ยวนํา 3 เฟส 50-Hz ที่เชื่อมต่อดาวโรเตอร์ให้ 500 V (r.m.s.) หยุดนิ่งระหว่างวงแหวนสลิปบนวงจรเปิด คํานวณกระแสและตัวประกอบกําลังเมื่อหยุดนิ่งเมื่อขดลวดโรเตอร์เชื่อมต่อกับวงจรภายนอกที่เชื่อมต่อกับดาวซึ่งแต่ละเฟสมีความต้านทาน 10 Ωและการเหนี่ยวนํา 0.04 H ความต้านทานต่อเฟสของขดลวดโรเตอร์คือ 0.2 Ω และการเหนี่ยวนําคือ 0.04 H.  นอกจากนี้ให้คํานวณตัวประกอบกระแสและกําลังเมื่อแหวนลื่นลัดวงจรและมอเตอร์ทํางานด้วยการลื่นไถล 5 เปอร์เซ็นต์ สมมติว่าฟลักซ์คงที่ [10.67 A; 0.376; 21.95 A; 0.303||

4.
A 3-phase, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill
between the slip-rings on open-circuit. Calculate the current and power factor at standstill when the
rotor winding is joined to a star-connected external circuit, each phase of which has a resistance of
10 2 and an inductance of 0.04 H. The resistance per phase of the rotor winding is 0.2 £2 and its
inductance is 0.04 H.
Also, calculate the current and power factor when the slip-rings are short-circuited and the motor is
running with a slip of 5 per cent. Assume the flux to remain constant.
[10.67 A; 0.376; 21.95 A; 0.303]
Transcribed Image Text:4. A 3-phase, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill between the slip-rings on open-circuit. Calculate the current and power factor at standstill when the rotor winding is joined to a star-connected external circuit, each phase of which has a resistance of 10 2 and an inductance of 0.04 H. The resistance per phase of the rotor winding is 0.2 £2 and its inductance is 0.04 H. Also, calculate the current and power factor when the slip-rings are short-circuited and the motor is running with a slip of 5 per cent. Assume the flux to remain constant. [10.67 A; 0.376; 21.95 A; 0.303]
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