Question

A 3-phase, 600 kVA, 600 V, 60 Hz, 16 pole, Y-connected, round rotor synchronous motor has Xs = 0.492 22 and a negligible armature resistance. The motor is supplied from a 589V infinity bus, and draws 520 kW of real power at a 0.9 leading power factor. Its mechanical loss at the synchronous speed is 20 kW and the core loss is 15 kW. a) [7 marks] Calculate the generated voltage Ef , the load angel 8, and the efficiency of the motor. b) [4 marks] What is the maximum torque this motor can deliver to the load without losing synchronism? c) [6 mark] If the above motor has a double-layer winding consisting of 5-turn coils, wound on a 144 slot stator with the coils in each phase connected to form two parallel paths, what is magnetic flux that each pole need to produce under the operation in (a). d) [3 marks] Explain what is a synchronous condenser (or synchronous capacitor) and its applications. What will be the active power drawn by the above motor, if it is used as a synchronous condenser?

Answer 1

9 a ubora 34 60okut, boov = 60tt3, P=16, x3=0.492, 42589, Pn - Vem 3you. Pandokul, Casde og leading da 25.89. mechanical losses - poku, iron, for Xose losses = 15kw sofer jy 3. ^ Jald. v to = El-stj Jald ts. 2) EL-SF Lo - 3X; Ia (d. = 340 - j 0.492 x 566.35 (25.89 = 529.335 v 1–28.50. Ef pn = 525.335. 7=13x525 335 = 909.906 e volts. &= 28.50 – load angle. it Poutput Pinput input Pinput - Total losses Pinput xoo 520k- (20ktisk) 520k xrood 93.26 % b) the maximum power out with out lossing sys- Chronics (8=90) – Pong - EU 909.906+ 589 o.u92

- Pmax= 1089.298 kwalts. (ws luns Tan Phax & 1089.2988003) 60. 47.12 = 23.115 KN. Tomax - Ws 1 = 47.12 grad/sec (20T . 1201y h120T 12 1207. (20 c) double layer CEs Saluu, Thors= 5 Love Total wo of Tuons - (aux5 . = 720 Tuoms. 1207 & 81207. No. of Tuons/pnage=720 = 20. each parall patts twins ... = 20 = 120 Two parallel touch Pen Phase - www.fed Tpni Kp.kd. T kp=l for 2) 525.335= 4.44 x 6ox dx120. C. =) de 925.335 uuux 60x120 -= 0.01643 wb. = 16.433 mob. Full el Pitch concertatey Doan over encitation. Synchronous motor with No-load on it is called as Synchronous condem ces (or Synchnous capacitor. It is used for power factor correction.