GER3688B - GE Generators - An Overview - GE Energy

More documents

Recommendations

Info

GER-3688B restructure its aircooled machines. A consequence of the historical development of the turbinegener- ator market was that two lines of generators evolved, one for steam turbine applications and the other for gas turbine applications, with little standardization between the designs. As GE embarked on this design restructuring, it took the opportunity to look at other issues which GE judged were criti- cal to its ability to maintain leadership in the design and manufacture of this size generator. Among these issues were performance parameters, availability of features, cycle time and cost effectiveness. MARKET NEEDS The basic design of a generator, while influ- enced primarily by material and electromagnetic properties, is also impacted by market requirements. Hence, customer discussions as well as recent market trends are used in the development of a final generator design. Some of these include: winding temperature rise, industry standards, generator ratings, etc. TEMPERATURE RISES In the early 1970s GE introduced insulation systems capable of operating at class F temperatures (155 C, 311 F) for the life of the generator. This enabled a significant uprating of generator designs (about 10%) with a minimal increase in cost. To capitalize on this technical capability, GE designed generators with Class F insulation and Class F rises. Many such generators built by GE are in service and operating successfully at Class F temperatures. However, the trend in recent specifications has been toward Class F insulation systems operating at Class B temperatures. In order to be responsive to these requirements, the new designs will operate at Class B temperatures according to ANSI and IEC standards. GENERATOR RATINGS In a rapidly developing technology, such as that of the combustion turbine, it is inevitable that the output of a given gas turbine frame size will be increased from time to time. This has required redesign of the generator to keep pace with the rise in turbine output. The ratings of the generators designed to match the gas turbine frame sizes have been set so that the generator will meet or exceed the gas turbine capability over the full operating temperature range, taking into account the expected turbine upratings duriiig the life- time of the design. Another important consideratioil that affects the generator rating which must be taken into 2 account is the use of steam and water injection for NO, control. The output of the gas turbine can increase by 5% or more above its dry IS0 rating, depending on the level of steam or water injection required to meet the emission requirements. An approach that results in the generator having suf- ficient capacity to match the gas turbine at the required NO, requirements has been factored into the generator rating. STANDARDS All new designs will meet the requirements of the applicable ANSI and IEC standards, as did the older designs. RELIABILITY Particular attention has been paid to known problem areas based on inservice generator experi- ence. The new designs strive for a high level of reliability and availability through attention to detail design and to the problems that have caused down- time on older designs. In addition, the reliability of the product will improve through design simplifica- tion and standardization, discussed below. PRODUCT STANDARDIZATION Standardization of the product line has significant benefits both to the user and to the manufacturer. From the user’s viewpoint, the standardization of the product line translates into a simpler machine with fewer unique parts, easier spare parts access and the reliability benefit of a larger fleet of identical machines, with the rapid identifi- cation of any performance problems that this brings. The benefits to the manufacturer are that, with fewer unique parts to track and check, fewer different assemblies to build and fewer drawings to keep up to date, the job of building a highqual- ity machine becomes simpler. Standardization is being implemented at three levels. At the highest level, the number of different designs can be reduced by careful selection of generator ratings and the use of common designs for gas and steam turbines. At the time the redesign project was begun, there were 17 unique air-cooled generator designs between 12 MVA and 100 MVA. With careful choice this has been reduced to six basic electromagnetic designs. The second level of standardization is illustrated in Figure 2. This shows the high level of standardization achieved in covering the basic config- urations of the generator for the Frame 6 gas turbine (designated 6A3), 50 Hz or 60 Hz, open
Design Option 6A3 6OHz 5oHz 6OHZ Generator Component TEWAC ov TEWAC ov BSBSBSBS Frame.. ............................................... . .. . , Core.. ............................................... . . .. . . . . Base ................................................. . . . . l . l Slator Bar 50 Hz.. ............................... . . Stator Bar 60 Hz ............................... l . t f Brushless Exe .................................... * . Static Ext.. ........................................ * 1 . ov Roof.. .......................................... t * l TRNAC Roof.. ...................................... Rotor Forging.. .................................. - ... . . l Rotor Copper ................................... l . l ..... Rotor Edg. 60 Hz ............................. . l .. Rotor Wdg. 60 Hz.. ............................. , . Rotor Slot Width ............................... . . . .... Rotor Slot Depth 50 Hz .................... t t l . Rotor Slot Depth 60 Hz .................... l * t . * .%me Canp~nent Applied to Deoign Option ventilated (OV) or totally enclosed (TEWAC) , and brushless or static excitation. For example, the stator frame, core and base, and the rotor forging and rotor copper cross section are identical for any combination of these features. The only dif- ference between the 50-Hz stator and the 60-Hz stator is the different stator bar. Everything else is the same. This component standardization can be extended to other ratings when the same compo nent is used for two different machines. For example, the generator base is the same for the Frame 5 generator as it is for the Frame 6 generator. In B - Brushless Excitation S - Static Excitation Figure 2. Generator standardization GER-3688B GT164SOA addition, while the gas turbines are the primary application of the new air-cooled generators, they can and have been applied with steam turbine drives as well (Figure 3). The most detailed level of standardization is with hardware such as fasteners and small compo nents. A carefully constructed list of preferred hardware has been developed and the number of different nuts, bolts and similar items has been drastically reduced. The impact of standardization is illustrated in Figure 4, which shows the reduction in the number of parts and drawings required to build a sin- I- REL. # OF PARTS REL. # OF DRAWINGS OLD DESIGN NEW DESIGN 1.0 0.6 1.0 0.7 GT19263 GT1649’ Figure 3. Air-cooled steam turbine generator Figure 4. Impact of standardization 3 ,
Page 1: GE Generators - An Overview James J
Page 6 and 7: GER-3688B gle new design as compare
Page 8 and 9: GER-3688B STATOR PUNCHINGS--, VENTI
Page 10 and 11: GER-3688B COll Wedge creepage BlWk
Page 12 and 13: GER-3688B - G02A-00-043 / Figure 17
Page 14 and 15: GER-3688B Creepage Block Copper Wmd
Page 16: GER-3688B The design of modern gene

GER3688B - GE Generators - An Overview - GE Energy

Create successful ePaper yourself

Delete template?

Save as template?