Tham khảo tài liệu 'electric machinery fundamentals (solutions manual) part 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 5 Synchronous Generators 5-1. At a location in Europe it is necessary to supply 300 kW of 60-Hz power. The only power sources available operate at 50 Hz. It is decided to generate the power by means of a motor-generator set consisting of a synchronous motor driving a synchronous generator. How many poles should each of the two machines have in order to convert 50-Hz power to 60-Hz power Solution The speed of a synchronous machine is related to its frequency by the equation n 12if-m To make a 50 Hz and a 60 Hz machine have the same mechanical speed so that they can be coupled together we see that _ 120 5 0_Hz 120 60 Hz n 7 10 P P 2 _P_ 6__12 _ P 5 10 Therefore a 10-pole synchronous motor must be coupled to a 12-pole synchronous generator to accomplish this frequency conversion. 5-2. A 2300-V 1000-kVA 60-Hz two-pole Y-connected synchronous generator has a synchronous reactance of and an armature resistance of . At 60 Hz its friction and windage losses are 24 kW and its core losses are 18 kW. The field circuit has a dc voltage of 200 V and the maximum I F is 10 A. The resistance of the field circuit is adjustable over the range from 20 to 200 . The OCC of this generator is shown in Figure P5-1. a How much field current is required to make VT equal to 2300 V when the generator is running at no load b What is the internal generated voltage of this machine at rated conditions c How much field current is required to make VT equal to 2300 V when the generator is running at rated conditions d How much power and torque must the generator s prime mover be capable of supplying e Construct a capability curve for this generator. Note An electronic version of this open circuit characteristic can be found in fil which can be used with MATLAB programs. Column 1 contains field current in amps and column 2 contains open-circuit termina voltage in 109 Solution
