Tham khảo tài liệu 'electric machinery fundamentals power & energy_7', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Ea V Problems 5-11 to 5-21 refer to a two-pole Y-connected synchronous generator rated at 470 kVA 480 V 60 Hz and PF lagging. Its armature resistance RA is Q. The core losses of this generator at rated conditions are 7 kW and the friction and windage losses are 8 kW. The open-circuit and short-circuit characteristics are shown in Figure P5-2. 127 Field current A _ Note An electronic version of the saturated open circuit characteristic can be found in file and an electronic version of the air-gap characteristic can be found in file . These files can be used with MATLAB programs. Column 1 contains field current in amps and column 2 contains open-circuit terminal voltage in volts. An electronic version of the short circuit characteristic can be found in file . Column 1 contains field current in amps and column 2 contains short-circuit terminal current in 5-11. a What is the saturated synchronous reactance of this generator at the rated conditions b What is the unsaturated synchronous reactance of this generator c Plot the saturated synchronous reactance of this generator as a function of load. Solution a The rated armature current for this generator is Ia h s 4 565 A L V3 VT V3 480 V The field current required to produce this much short-circuit current may be read from the SCC. It is A3. The open circuit voltage at A is 880 V4 so the open-circuit phase voltage EA is 880 V3 508 V. The approximate saturated synchronous reactance XS is 3 If you have MATLAB available you can use the file p52_scc. dat and the interpl function to look up this value as shown below. Note that column 1 of p52_scc contains field current and column 2 contains short-circuit terminal current. load if interpl p52_scc 2 p52_scc 1 565 if 128 Xs 508 V 565 A Q b The .
