Standard Technical Features of BTG System for Supercritical 660 ...

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsc) Margin Each excitation system channel shall bedesigned to continuously carry at least 110%of the rated machine excitation current at therated output of the machine and highercurrents for short time duty. Short time dutyas mentioned above shall be on MCR base asper clause 1.14 of part III in VDE 530.d) Excitation systemresponse timee) Excitation responseratiof) Excitation systemceiling voltage2>1.5 times rated load excitation voltage.g) Field forcing capability Each excitation system channel shall becapable of supplying without damage to anyof the components, the field forcing voltageand current of the system for a period of 10seconds without exceeding the limits oftemperature for rectifier junction and sink,when the equipment starts at normal operatingtemperature.iii) Automatic voltage regulator (AVR)a) Voltage regulator The excitation system shall be designed insuch a manner that due to any single fault inAVR firing circuit pulse transformer,rectifying elements in any channel etc.excitation system shall be available with itsfull capacity. All rectifying elements shallhave over voltage and short circuit protection.b) Number of channels Two numbers fully equipped automaticchannels having independent inputs andautomatic changeover shall be provided.Either channel shall be capable of being themain or standby. Either channel shall becapable of being selected as manual also.c) Characteristics1. Auto control range (±)10% of rated terminal voltage in all modesfor voltage level adjustments of generatoroperation.2. Frequency range of 47.5Hz to 51.5Hz.operation3. Accuracy at whichgenerator voltage tobe heldBetter than 0.5% of the set value over thewhole load range of the generator.133