Example The 0.C.C. of a d.c. generator driven at 400 rev/min is as follows : Field current (A) 2 3 4 5 7 8 9 Terminal volts 110 155 186 212 230 246 260 271 (a) voltage to which the machine will excite when run as a shunt generator at 400 rev/min with shunt field resistance equal to 34 2. (b) resistance of shunt circuit to reduce the O.C. voltage to 220 V. (c) critical value of the shunt field circuit resistance. (d) the critical speed when the field circuit resistance is 34 Q. (e) lowest possible speed at which an 0.C. voltage of 225 V can be obtained. 100

Example The 0.C.C. of a d.c. generator driven at 400 rev/min is as follows : Field current (A) 2 3 4 5 7 8 9 Terminal volts 110 155 186 212 230 246 260 271 (a) voltage to which the machine will excite when run as a shunt generator at 400 rev/min with shunt field resistance equal to 34 2. (b) resistance of shunt circuit to reduce the O.C. voltage to 220 V. (c) critical value of the shunt field circuit resistance. (d) the critical speed when the field circuit resistance is 34 Q. (e) lowest possible speed at which an 0.C. voltage of 225 V can be obtained. 100

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter11: Transient Stability

Section: Chapter Questions

Problem 11.3P

See similar textbooks

Similar questions

Electrical Engineering Problem. Please help to provide correct solution for the problem. Please show neat solution Thanks. A 100kW, 230V, shunt generator has an armature resistance and field resistance of 0.05Ωand 57.5Ω. If the generator operates at rated voltage. SPL is 1.8kW,a) At what load does the generator achieve maximum efficiency?b) What is the value of this maximum efficiency?
A gas turbine, 2-pole, 3? synchronous generator rated at 200 MW is connected to the grid (presumed to be an infinite bus). The electrical operating frequency of the grid is 60 Hz, and the slope of the frequency-power curve for the generator is 15 MW/Hz. a. If the no-load setpoint for the generator is set to 63.5 Hz, how much active power will the generator provide to the grid? b. Neglecting system losses, what is the torque provided by the gas turbine? c. What would happen if the no-load setpoint for the generator is set to 59 Hz?
A 10kW 220 volt compound generator is operated at no load at theproper armature voltage and speed, from which the stray power losscalculations are determined to be 705 watts. The shunt field resistance is110 ohms, the armature resistance is 0.265 ohm, and the series fieldresistance is 0.035 ohm. Assume a 2 volt brush drop and (a) calculate thefull load efficiency. (b) Calculate also the maximum efficiency.
The open-circuit characteristic of a shunt generator when driven at normal speed is as;Field current (A)0.51.01.52.02.53.03.5O.C. volts (V)54107152185210230240The resistance of armature circuit is 0.1 Ω. Due to armature reaction the effective field current is given by the relation Ish (eff.) = Ish − 0.003 Ia. Find the shunt field circuit resistance that will give a terminal voltage of 220 V with normal speed (a) on open circuit (b) at a load current of 100 A. Also find (c) number of series turns for level compounding at 220 V with 100 A armature current; take number of shunts turns per pole as 1200 and (d) No. of series turns for over-compounding giving a terminal voltage of 220 V at no-load and 230 V with 100 A armature current.
The open-circuit characteristic of a shunt generator when driven at normal speed is as;Field current (A)0.51.01.52.02.53.03.5O.C. volts (V)54107152185210230240The resistance of armature circuit is 0.1 Ω. Due to armature reaction the effective field current is given by the relation Ish (eff.) = Ish − 0.003 Ia. Find the shunt field circuit resistance that will give a terminal voltage of 220 V with normal speed (a) on open circuit (b) at a load current of 100 A. Also find (c) number of series turns for level compounding at 220 V with 100 A armature current; take number of shunts turns per pole as 1200 and (d) No. of series turns for over-compounding giving a terminal voltage of 220 V at no-load and 230 V with 100 A armature current.please answer only part C and D
An A 20kW DC shunt generator having an armature circuit resistance of 0.8Ω and a field resistance of 140 Ω, generates a terminal voltage of 230V at full load. Determine the total iron, friction and windage losses if the efficiency of the generator at full load= 83%.
Three de shunt generators in parallel running each having an armature resistance of 0.2ohms. running at the same speed and excited to give equal share of total load of 200 kW at a terminal voltage of 500V into a load of fixed machine. If the field current of one generator is raised by 2%, the other remaining unchanged, calculate the output power of each machine and their terminal voltage under this conditions. Assume the speed remains constant and the flux is proportional to field current.
A long-shunt compound d.c. generator with armature, series field and shunt field resistance of 0.5, 0.4 and 250 Ω respectively gave the following readings when run at constant speed : Load current (A) : 0 10 20 30 40Terminal p.d. (V) : 480 478 475 471 467 Plot the curve of internal generated e.m.f. against load current. Explain fully the steps by which this curve is obtained and tabulate the values from which it is plotted.
A 230V shunt motor has an armature resistance of 0.28Ω and a field resistance of 115Ω. At no-load, the line current is 8A and the speed is 2300rpm. What is the speed when the line current is 52A? Assume brush drops of 1V at no-load and 3V at load condition and constant flux density. 2154rpm 2212rpm 2178rpm 2155rpm
EMachines A 100 MVA, 11.5 kV 0.8 pf lagging 50-Hz two pole Y-connected synchronous generator has a per-unitsynchronous reactance of 0.8 and per-unit armature resistance of 0.012. A. What is its synchronous reactance and armature resistance in ohms?B. What is the magnitude of the internal generated voltage at the rated conditions? What is its torque angleat these conditions?C. Ignoring losses in this generator, what torque must be applied to its shaft by the prime mover at fullload?
A 70-MVA, 69.3-kV, three-phase round-rotor synchronous generator has a synchronous reactance of 14 ohm per phase and negligible armature resistance. 1) The generator is delivering rated power at 0.87 power factor lagging at the rated terminal voltage to an infinite bus bar (Fig. 1). Determine the magnitude of the generated emf per phase and the power angle δ. 2) The generator is delivering 53.5 MW to the bus bar at the rated voltage with its field current adjusted for a generated emf of 46 kV per phase. Determine the armature current and the power factor. Is the power factor is lagging or leading? 3) Given that the generator is operating at the excitation voltage of Part (1), determine the maximum steady-state power which the machine can deliver without losing synchronism. Find the armature current corresponding to this maximum power.
A 1500KVA, 11KV, 50Hz, Star connected synchronous generator is tested by operating it as a synchronous motor on no-load. The results are as follows: When operated as a synchronous motor on load the power input to the motor is 55.8KW and the armature line current is 70A. The excitation of 38.6A at 250V dc gives the normal open-circuit voltage. DC resistance test: dc line voltage 17.5V and dc line current 70A. Take the effective resistance as 1.6 times the dc resistance. Calculate the efficiency of the machine on 80% of the full-load and 0.75 power factor lagging