A synchronous generator connected to a 50 Hz infinite bus bar through a transformer and transmission line has an inertia constant of 3.5 MJ/MVA. The synchro- nous reactance of the generator is 0.8 pu and total reactance of the transformer and trans- mission line is 1.2 pu. If no load voltage of the generator is 1.15 pu, calculate the frequency of natural oscillations of the generator rotor if the generator is loaded to (1) 50% and (ii) 75% of its max power limit.

A synchronous generator connected to a 50 Hz infinite bus bar through a transformer and transmission line has an inertia constant of 3.5 MJ/MVA. The synchro- nous reactance of the generator is 0.8 pu and total reactance of the transformer and trans- mission line is 1.2 pu. If no load voltage of the generator is 1.15 pu, calculate the frequency of natural oscillations of the generator rotor if the generator is loaded to (1) 50% and (ii) 75% of its max power limit.

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter39: Synchronous Motor Operation

Section: Chapter Questions

Problem 14SQ: Induction motors and welding transformers require magnetizing current, which causes a. lagging power...

See similar textbooks

Similar questions

Two identical, 3-phase, Y-connected alternators A and B share equally a load of 10MW at 33kV at 0.8pf lagging. The synchronous reactance of each machine is 4 ohms per phase and the armature resistance is negligible. Alternator A has its field excitation adjusted to carry 125A lagging current. What is the current supplied by alternator B?
2. A synchronous generator is connected to an inductive load, please draw phasor diagram to show the relationship between the internal generated voltage of the generator and the terminal voltage across the load. If the same generator is connected to a capacitive load, please draw phasor diagram to show the relationship between the internal generated voltage of the generator and the terminal voltage cross the load again. Explain the difference of the terminal voltage responses at these two types of loads.
A 4 pole dc generator with duplex wave winding has 48 slots and four elements per slot. The flux perpole is 2.5 x 10 Maxwells and the speed of the prime mover is 30 rpm. What is the average generatedarmature voltage? Neglecting brush drop.
The reactance of a generator is given as 0.1 pu based on the generator of 17 KV, 300 MVA. Determine the pu reactance on a base of 17 KV, 250 MVA. New pu reactance is.......
8-pole 3-phase star-connected alternator with 144 grooves in its armature rotates at 900 rpm. There are 12 conductors in each groove in the armature of the alternator. The magnetic flux of one pole is 1.8.10 ^ 6 maxwels. Coils (1-16) were wound in -15 steps. Accordingly, find the phase and interphase voltages induced in the inductor of the alternator. (The speed of the alternator will be taken as synchronous speed ns.)
A 6-pole ,3 phase , 60 cycle alternator has 12 slots per pole and four conductor per slot. The winding is 5/6 pitch. There are 2,500,000 Maxwell ( 0.025 weber ) entering the armature from each north pole, and this flux sinusoidally distributed along the air gap. The armature coils are all connected in series , The winding is wye connected. Determine the open circuit emf of the alternator.
A 9.9 kV, Y-connected, 3 phase alternator has a synchronous reactance of 8 ohms per phase and negligible resistance. At a certain field current the armature is known to induce 8.2 kV per phase. Calculate the power that can be developed by the alternator at this excitation.
Two identical three-phase Alternators A and B share equally a load of 10 MVA at 33 KV and 80% lagging power factor. The synchronous reactance of each generator is 4 ohms per phase and the armature resistance is negligible. Alternator A has its field excitation adjusted to carry a25 amperes at lagging power factor. What is the current delivered by Alternator B ?
A synchronous generator runs at 250 rpm and generators at 60HZ. There are 240 slots each containing 5 conductors arranged in full-pitched winding for three-phase star connection. All the conductors of each phase are in series and the flux per pole at no-load distributed sinusoidally over the pole pitch is 2.5 x106 Maxwell. What is the emf induced in each winding and the terminal voltage?
A 400 v, 50 Hz, three phase alternators, rated at 75 kVA, is star connected and driven at 1000 r/min. The windings of the alternator have a resistance, per phase, of 0.03 Ω and synchronous reactance, at 50 Hz per phase, of j0.325 Ω. The stator of the alternator has 108 slots, with 8 conductors, per slots, in a double layer. The maximum pole flux is 8.772 x 10-3 Wb. To improve the wave form only 80% of the pole pitch is wound. Determine the smallest lagging power factor at which the alternator can deliver its rated load
A single-phase synchronous generator has a rated output of 500 kVA at a terminal voltage of 3300 V. The stator winding has a resistance of 0.6 ohms and a synchronous reactance of 4.0ohms. Calculate the percentage voltage regulation at a power factor of 0.8 lagging. Sketch the phasor diagram.
The net cross section of a transformer is 20 square inches. The maximum fluxdensity is 11 kilogausses. The frequency is 60 Hz. If there are 1,000 turns in theprimary, determine the primary induced emf.