Abstract:
A wind powered electric generator is provided with variable electric power output in accordance with wind speed. The wind powered electric generator has a multiple coil arrangement that allows electric power to be produced at low wind speeds as well as at high wind speeds. Also provided is multiple sealed coil packs with a magnetic coupling adjustment mechanism as well as a method and control system for controlling 0 through 100 percent power output of the wind powered electric generator in relation to wind speed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         DESCRIPTION OF ATTACHED APPENDIX  
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    This invention relates generally to the field of power generation and more specifically to a wind powered electric generator, in particular the invention relates to a megawatt wind powered electric generator that allows electric power to be produced at low wind speeds as well as at high wind speeds.  
           [0005]    The present invention relates to a wind powered electric generator, in particular the invention relates to a megawatt wind powered electric generator that allows electric power to be produced at low wind speeds as well as at high wind speeds.  
           [0006]    Various wind powered machines have been utilized over the years to pump water from wells and in later years to generate electric power. Early wind powered electric generators were widely used on farms that could not connect to commercial electric power due to long distances encountered to the nearest power lines. Today with pollution concerns from conventional fossil fueled electric power plants and a growing worldwide electrical generating capacity shortfall wind powered electric generators are now being used to supplement existing sources of electrical power. Several different types of wind powered electric generators are used to supplement existing electric power.  
           [0007]    One type of wind powered electric generator employs moving permanent magnets to induce magnetic fields in coils of wire to produce electric power. When wind powered electric generators that employ permanent magnets are used to supplement existing power sources problems arise as to the control of electrical power output in low and high wind speeds limiting the use of permanent magnet type generators to small low power wind generating applications.  
           [0008]    It is desirable to have a wind powered electric generator that utilizes permanent magnets while producing a high electrical power output in the megawatt range.  
           [0009]    It is desirable to have a wind powered electric generator that does not require synchronization with existing power sources.  
           [0010]    It is desirable to have a wind powered electric generator that produces electrical energy during low wind speed conditions to maximize the wind powered generators total yearly output of electric power.  
           [0011]    Another concern in the use of wind powered electric generators is cost per kilowatt-hour of electrical energy produced. This includes the first cost to purchase the wind powered electric generator as well as the cost to maintain the electric generator during the generators life span. The lower the cost of maintenance performed on a wind powered electric generator, the more usable a wind powered electric generator becomes. It is desirable to have a wind powered electric generator design that allows unattended operation for long periods of time while requiring very little maintenance.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    The primary object of the invention is to take advantage of the low wind speeds prevalent in most areas to make wind power an economical power production technology.  
           [0013]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets to produce electric power during low and high wind speeds.  
           [0014]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets with a multiple sealed coil arrangement and a magnetic coupling adjustment mechanism to control the electrical output of the wind powered generator in accordance with wind speed.  
           [0015]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets to produce a high power output in the megawatt range.  
           [0016]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets that does not require synchronization with existing power sources.  
           [0017]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets that uses no more generator coils than required to produce electric power.  
           [0018]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets to produce electric power during low wind speed conditions to maximize the wind powered generators total yearly output of electric power.  
           [0019]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets that is low in initial cost and is inexpensive to maintain during the service life of the generator.  
           [0020]    Another object of the invention is to provide a wind powered electric generator that utilizes moving permanent magnets that is simple to repair and is able to operate unattended for long periods of time without maintenance.  
           [0021]    Another object of the invention is to provide a wind powered electric generator that allows continued generation of electric power while operating with one or more defective generator coils eliminating the need for a shutdown to make emergency repairs to the generator.  
           [0022]    Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.  
           [0023]    In accordance with a preferred embodiment of the invention, there is disclosed a megawatt-level wind powered electric generator comprising: A series of coil packs that allow for modular construction, and coil packs that allow the generator to produce power proportional to the wind speed.  
           [0024]    The present invention relates to a wind powered electric generator mechanical arrangement and control. The generator comprises of a rotating propeller directly connected to a horizontal rotating shaft mounted in bearings and alternating pole permanent magnets axially mounted in relation to the shaft to a rotating drum that is affixed directly to the horizontal rotating shaft. A stationary outer drum with end plates support the rotating shaft bearings and a multitude of moveable coil packs that generate electricity when in alignment with the magnetic field of the permanent magnets mounted to the rotating drum.  
           [0025]    Moveable coil packs consists of multiple C shaped layered stamped steel cores wrapped with several layers of wire forming a wire coil. Included with each coil is a liquid cooled bridge rectifier and fuses. In addition a liquid filled cooling coil is wrapped around the wire coils of each C shaped core. All parts are encapsulated in a potting compound forming a solid sealed rectangular coil pack structure with the legs of the C shaped cores protruding through the bottom of the coil pack.  
           [0026]    The coil pack has provisions for a flexible electric cord with locking plug connected to the bridge rectifiers, fuses and for flexible braided hose connections to cool the liquid cooled bridge rectifier, wire coils of the coil pack with circulating cooling liquid. The coil packs are supported with spring return pneumatic cylinders and are located in rectangular cut holes in the stationary outer drum with guide plates to permit radial movement of the coil packs in relation to the stationary outer drum during actuation of the spring return pneumatic cylinders. The legs of the C shaped cores that protrude through the bottom of the coil pack move in and out of alignment with the magnetic field of the alternating poles of the magnets mounted to the inner rotating drum during movement of the coil pack increasing or decreasing the output of electric current from the coil pack.  
           [0027]    Coil pack cords are plugged in to locking sockets located at the each end of the generators stationary outer drum and the DC power produced by the generator is connected with DC link cables to a inverter for conversion from DC current to AC current connected to a alternating current three-phase utility power line for distribution to consumers of electric power. Coil pack flexible braided hoses are connected to a common liquid filled header located at the middle of the generators stationary outer drum that in turn connects to an external to the generator fan coil fluid to air heat exchanger with a circulating pump to remove heat from the generator coil packs during power generation.  
           [0028]    The loading of the generator coil packs in relation to available wind speed controls the shaft speed of the generator. The operating shaft speed is maintained at a predetermined target speed allowing the maximum amount of available generator shaft power to be converted to electric power. In addition only the coil packs that are required are used to produce electric power as the remaining unused coil packs are physically removed from the magnetic circuit of the alternating pole permanent magnets mounted on the inner rotating drum in turn removing all unneeded magnetic coupling and the resultant parasitic drag on the rotating shaft.  
           [0029]    When the generator shaft speed increases due to higher wind speed above the predetermined target shaft speed more coil packs are loaded causing the DC link current to rise and the DC to AC inverter supplies more power to the three phase utility power line in turn placing more load on the generator shaft returning the generator shaft speed to the predetermined target shaft speed.  
           [0030]    When the generator shaft speed decreases due to lower wind speed below the predetermined target shaft speed less coil packs are loaded causing the DC link current to fall and the DC to AC inverter supplies less power to the three phase utility power line in turn placing less load on the generator shaft returning the generator shaft speed to the predetermined target shaft speed.  
           [0031]    In addition the coil pack loading sequence allows an infinite modulated coil pack loading between the minimum electrical power output of the generator and the maximum electrical power output of the generator through the use of the generator control systems pneumatic transducers that allow modulated control of the spring return pneumatic cylinders. The spring return pneumatic actuated cylinders react quickly to changing wind speeds to load and unload the coil packs in a predetermined sequence maintaining the predetermined target speed of the generator shaft and a stable DC link power output to the DC to AC inverter.  
           [0032]    Below a predetermined generator shaft speed the generator is fully unloaded and the generator shaft speed is allowed to float until the predetermined target speed is reached. At this time the loading of the coil packs begins up to the ability of the generator to maintain the predetermined shaft target speed. At very high wind speeds all coil packs are loaded to the maximum loading producing the maximum rated output of the generator.  
           [0033]    At wind speeds above the maximum of the predetermined shaft target speed built in airfoils on the propeller blades limit the generator shaft speed to a predetermined safe speed to keep the generator from operating in an over-speed condition. A brake disc mounted to the generator shaft on the opposite end of the generator from the propeller with calipers with brake pads mounted to the outer drum end plate are activated if an emergency over-speed condition exists that exceeds a predetermined safe generator shaft speed stopping the rotation of the generator shaft.  
           [0034]    An optical encoder mounted on the stationary outer drum end plate opposite the propeller monitors the generator shaft speed through equally spaced holes in the brake disc that is mounted to the generator shaft. The optical encoder measures the generator shaft speed of rotation and sends a speed signal to the generators control system, which in turn controls the coil pack loading of the generator.  
           [0035]    Maintenance involves yearly lubrication of two bearings. If a defective coil should develop the coil pack may be quickly replaced, as they are easily accessible on the stationary outer drum and are attached with two bolts. In addition the generator will continue to operate with one or more defective coil packs and replacement may be scheduled during regular maintenance avoiding an emergency generator shutdown for repairs.  
           [0036]    The stationary outer drum is mounted on a on a rotating platform that allows the propeller of the generator to be properly orientated with respect to the direction of the wind. The rotating platform is supported on a suitable high vertical tower. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.  
         [0038]    [0038]FIG. 1 shows a cross section view of various aspects of the wind powered electric generator.  
         [0039]    [0039]FIG. 2 shows a top view of one of the wind powered generators coil packs.  
         [0040]    [0040]FIG. 3 shows a side view of the coil pack shown in FIG. 2.  
         [0041]    [0041]FIG. 4 shows a side view detail of one coil of the coil pack from FIGS. 2 and 3.  
         [0042]    [0042]FIG. 5 shows a end view detail of one coil of the coil pack shown in FIG. 3.  
         [0043]    [0043]FIG. 6 shows a side view of the front end plate of the generator shown in FIG. 1.  
         [0044]    [0044]FIG. 7 shows a end view of the front end plate of the generator shown in FIG. 6.  
         [0045]    [0045]FIG. 8 shows a side view of the rear end plate of the generator shown in FIG. 1.  
         [0046]    [0046]FIG. 9 shows a schematic electrical diagram of the coil pack shown in FIGS. 2 and 3.  
         [0047]    [0047]FIG. 10 shows a schematic fluid tubing diagram of the coil pack shown in FIGS. 2 and 3.  
         [0048]    [0048]FIG. 11 shows a schematic electrical diagram of the generator shown in FIG. 1.  
         [0049]    [0049]FIG. 12 shows a generator coil pack numbering arrangement.  
         [0050]    [0050]FIG. 13 shows a block diagram of a generator control system.  
         [0051]    [0051]FIG. 14 shows a detail side view of a cooling liquid header.  
         [0052]    [0052]FIG. 15 shows a detail top view of a cooling liquid header.  
         [0053]    [0053]FIG. 16 shows a block diagram of a cooling liquid fluid flow.  
         [0054]    [0054]FIG. 17 shows a end view of a rotating inner drum.  
         [0055]    [0055]FIG. 18 shows a side view of a rotating inner drum.  
         [0056]    [0056]FIG. 19 shows a detail side view of the rotating inner drum. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0057]    Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner.  
         [0058]    The figures are all schematic representations of the different portions of this invention. Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.  
         [0059]    With reference to FIG. 1, (side view) a stationary outer drum  54  with end plates  32  and  70 , bearings  100  and  74  support a rotating shaft  52 . Rotating inner drums  50   a  and  50   b  are attached to attached to rotating shaft  52 . One end of rotating shaft  52  has a propeller mounting hub  104  and propeller mounting bolts holes  102 . The other end of rotating shaft  52  has a disc brake rotor  72  attached with disc brake mounting bolts  76 . A Metal backed rubber dust seal  104  prevents entry of dust around rotating inner shaft  52 . Disc brake calipers with pads and mounting bolts  64  are mounted to rear end plate  70 . Also mounted to end plate  70  is optical encoder  78 . Sheet metal end cover  66  covers the rear end of the generator.  
         [0060]    With reference to FIG. 1 stationary outer drum  54  supports bus duct with bus bars and twist lock sockets  40 . Stationary outer drum  54  supports cooling liquid header  48 . Stationary outer drum  54  supports coil pack  42  and spring return pneumatic cylinder  58 . Front end plate  32  and rear end plate  70  are mounted to steel I beam of a rotating platform.  
         [0061]    With reference to FIG. 2 (top view) coil pack  42  from FIG. 1. Coil pack  42  is mounted in hole in stationary outer drum  120  using metal backed PTFE coil pack guides  110  that are held in place with mounting screws  116 . The spring return pneumatic cylinder rod  130  is fastened to coil pack spring return pneumatic cylinder mounting bracket with spring return pneumatic cylinder rod mounting nut  114 . Coil pack  42  outer housing  122  has mounted within it coil  124 . Rectifier  128  coil pack supply cooling header  140 , coil pack return cooling header  142 , minus coil pack wiring  144  and plus coil pack wiring  146 .  
         [0062]    With reference to FIG. 2 (top view) polyethylene mounting plate  118  provides a mounting location for cooling hoses supply and return  44 . a polyethylene mounting plate similar to  118  provides a mounting location for a two wire rubber cord  36 .  
         [0063]    With reference to FIG. 3 (side view) coil pack  42  from FIG. 1. screws  128  hold polyethylene mounting plate  118  in place. Fuse  150  protects rectifier  128 . Coil to rectifier wiring  152  connects coil to rectifier. Pneumatic tubing connection  132  is used to supply compressed air to the spring return pneumatic cylinder  58 . Mounted to rotating inner drum  50   a  is permanent magnet  134  attached to rotating inner drum with magnet mounting clip with bolts  138 .  
         [0064]    With reference to FIG. 4 (side view) of coil  124  from FIG. 2 protruding laminated transformer steel coil legs  136  protrude through bottom of coil pack housing  158 . Rectifier bonded to cooling coil  160 . Level of potting compound  154  holds coil  124  in place. Permanent magnet  134  from FIG. 2.  
         [0065]    With reference to FIG. 5 (end view) of coil  124  and from FIG. 2. level of potting compound  154  holds coil  124  in place. Cooling tubing  156  removes heat from coil  124 . Coil pack supply cooling header  140  is connected to one end of cooling tubing  156 . Coil pack return header  142  is connected to the other end of cooling tubing  156 .  
         [0066]    With reference to FIG. 6 (side view) of front end plate  32  from FIG. 1. Human form to indicate scale  126 .  
         [0067]    With reference to FIG. 7 (end view) of front end plate  32  from FIG. 1.  
         [0068]    With reference to FIG. 8 (side view) of rear end plate  70  from FIG. 1.  
         [0069]    With reference to FIG. 9 schematic electrical diagram of the coil pack shown in FIG. 2 and FIG. 3. Coil  124  is connected to rectifier  148  with coil to rectifier wiring  152 . Fuse protects rectifier  148 . Plus coil pack wiring  146  is connected to two wire rubber cord  36  and two wire rubber cord  36  is connected to twist lock plug  34 .  
         [0070]    With reference to FIG. 10 schematic fluid tubing diagram of the coil pack shown in FIG. 3. Cooling tubing  156  connects to coil pack supply cooling hoses supply and return.  
         [0071]    With reference to FIG. 11 schematic electrical diagram of the generator shown in FIG. 1 Bus duct with bus bars and twist lock sockets  40  is connected in parallel one through  40  to Section A DC link cables plus/minus  94 . Section A DC link cables plus/minus  94  are connected to A section disconnect  164   a  and A section fuses  166   a . A section DC to AC inverter  168   a  and to Three phase alternating current utility power line  170 .  
         [0072]    With reference to FIG. 11 schematic electrical diagram of the generator in FIG. 1 showing bus duct with bus bars and twist lock sockets  40  one through forty for A section of the generator. Section A DC link cables Plus and minus  94  connect bus duct with bus bars and twist lock sockets  40  to A section disconnect  164   a . is connected to A section fuses  166   a . A section fuses  166   a  are connected to A section DC to AC inverter  168   a  which is connected to three phase alternating current utility power line. B section of FIG. 11 is identical to A section.  
         [0073]    With reference to FIG. 12 generator coil pack numbering arrangement. Row A one through forty  172  provides the mounting arrangement for coil pack  42  around stationary outer drum  54  from FIG. 1. B section is identical to A section  
         [0074]    With reference to FIG. 13 block diagram of the generator control system. FIG. 13 shows the operation of the generator control system. Optical speed sensor  80  generates a signal indicating disc brake rotor with holes for optical speed sensor  72  and rotating shaft  52  from FIG. 1 rotational speed. The signal from the optical speed sensor  80  indicating generator shaft speed is sent to the input of generator control system  174 . The generator control system  174  sends output current signals one through twenty stages to analog output card for coil pack loading  176  which is then converted to a pneumatic output by I to P current to pneumatic transducer  182 . The pneumatic signal from the I to P current to pneumatic transducer  182  is sent to spring return pneumatic cylinder  58  to load coil pack  42   
         [0075]    With reference to FIG. 14 detail side view of a cooling liquid header. FIG. 14 shows the supply pipe of cooling header  92  and return pipe of cooling header  90  that is connected to cooling liquid header  48 . Shutoff ball valve  56  is mounted to cooling liquid header  48 . To the other end of shut off ball valve  56  is connected hose connection  46  Hose connection  46  connects to Coil pack  42  FIG. 1 via cooling hose supply and return  44 .  
         [0076]    With reference to FIG. 15 detail top view of a cooling liquid header shows the location of supply pipe of cooling header  92  and return pipe of cooling header  90  shown in FIG. 14.  
         [0077]    With reference to FIG. 16 block diagram of a cooling liquid flow. FIG. 16 Shows the liquid cooling flow through coil pack  42  FIG. 1 one through forty. Cooling liquid header  48  through return pipe of cooling header  90  connects to cooling liquid header connections  60  then to cooling fluid circulating pump  186 . Cooling fluid circulating pump  186  is connected to liquid to air heat exchanger  188  cooling fan  190  removes heat from Liquid to air heat exchanger  188 . Pressure tank  184  is connected to cooling liquid header connections  60 .  
         [0078]    With reference to FIG. 17 end view of a rotating inner drum. Rotating shaft  52  supports rotating inner drum support struts  192  through shaft collar  200 . shaft collar  200  is secured to rotating shaft  52  with set screws  198 . rotating inner drum support struts  192  support rotating inner drum  50 .  
         [0079]    With reference to FIG. 18 side view of a rotating inner drum shows a side view of rotating inner drum from FIG. 17 rotating shaft  52  and rotating inner drum  50 .  
         [0080]    With reference to FIG. 19 detail side view of the rotating inner drum shows the location of permanent magnets showing north and south poles  134  from FIG. 4 attached to rotating inner drum  50  from FIG. 17 with magnet mounting clips with bolts  138 . from FIG. 2  
         [0081]    The figures show schematic drawings of the invention. The parts on each figure are given by the reference numbers. 
         [0082]    [0082] 30  End plate bolts.  
         [0083]    [0083] 32  Front end plate.  
         [0084]    [0084] 34  Twist lock plug.  
         [0085]    [0085] 36  Two wire rubber cord.  
         [0086]    [0086] 38  Pneumatic tubing header.  
         [0087]    [0087] 40  Bus duct bus bars and twist lock sockets, A section.  
         [0088]    [0088] 42  Coil pack.  
         [0089]    [0089] 44  Cooling hoses supply and return.  
         [0090]    [0090] 46  Hose connection.  
         [0091]    [0091] 48  Cooling liquid header.  
         [0092]    [0092] 50  Rotating inner drum.  
         [0093]    [0093] 52  Rotating shaft.  
         [0094]    [0094] 54  Stationary outer drum.  
         [0095]    [0095] 56  Shutoff ball valve.  
         [0096]    [0096] 58  Pneumatic spring return cylinder.  
         [0097]    [0097] 60  Cooling liquid header connections.  
         [0098]    [0098] 62  Bus duct bus bars and twist lock sockets, B section.  
         [0099]    [0099] 64  Disc brake calipers.  
         [0100]    [0100] 66  Sheet metal end cover.  
         [0101]    [0101] 68  Pneumatic disc brake line.  
         [0102]    [0102] 70  Rear end plate.  
         [0103]    [0103] 72  Disc brake rotor.  
         [0104]    [0104] 74  Rear bearing.  
         [0105]    [0105] 76  Disc brake rotor mounting bolts.  
         [0106]    [0106] 78  Holes in disc brake rotor  
         [0107]    [0107] 80  Optical encoder.  
         [0108]    [0108] 82  Brake caliper air tubing.  
         [0109]    [0109] 84  Plug to connect optical encoder.  
         [0110]    [0110] 86  Section B DC link cables plus/minus to DC to AC inverter.  
         [0111]    [0111] 88  Steel I beam base plate.  
         [0112]    [0112] 90  Return pipe of cooling header.  
         [0113]    [0113] 92  Supply pipe of cooling header.  
         [0114]    [0114] 94  Section A DC link cables plus/minus to DC to AC inverter.  
         [0115]    [0115] 96  End plate bolts.  
         [0116]    [0116] 98  Bearing support.  
         [0117]    [0117] 100  Front bearing radial thrust type.  
         [0118]    [0118] 102  Propeller mounting bolts.  
         [0119]    [0119] 104  Propeller mounting flange.  
         [0120]    [0120] 106  Metal backed rubber dust seal.  
         [0121]    [0121] 108  Approximate center of gravity.  
         [0122]    [0122] 110  Metal backed PTFE coil pack guides.  
         [0123]    [0123] 112  Spring return pneumatic cylinder mounting bracket.  
         [0124]    [0124] 114  Spring return pneumatic cylinder rod mounting nut.  
         [0125]    [0125] 116  Mounting screws.  
         [0126]    [0126] 118  Polyethylene mounting plates.  
         [0127]    [0127] 120  Edge of rectangle hole in stationary outer drum.  
         [0128]    [0128] 122  Coil pack housing.  
         [0129]    [0129] 124  One coil of eight.  
         [0130]    [0130] 126  Human form.  
         [0131]    [0131] 128  Screws.  
         [0132]    [0132] 130  Spring return pneumatic cylinder rod.  
         [0133]    [0133] 132  Pneumatic tubing connection.  
         [0134]    [0134] 134  Permanent magnets.  
         [0135]    [0135] 136  Protruding laminated transformer steel coil legs.  
         [0136]    [0136] 138  Magnet mounting clips.  
         [0137]    [0137] 140  Coil pack supply cooling header.  
         [0138]    [0138] 142  Coil pack return cooling header.  
         [0139]    [0139] 144  Minus coil pack wiring.  
         [0140]    [0140] 146  Plus coil pack wiring.  
         [0141]    [0141] 148  Rectifier.  
         [0142]    [0142] 150  Fuses.  
         [0143]    [0143] 152  Coil to rectifier wiring.  
         [0144]    [0144] 154  Level of potting compound.  
         [0145]    [0145] 156  Cooling tubing.  
         [0146]    [0146] 158  Bottom of coil pack housing.  
         [0147]    [0147] 162  Tee connection.  
         [0148]    [0148] 164   a  A section disconnect.  
         [0149]    [0149] 164   b  B section disconnect.  
         [0150]    [0150] 166   a  A section fuses.  
         [0151]    [0151] 166   b  B section fuses.  
         [0152]    [0152] 168   a  A section DC to AC inverter.  
         [0153]    [0153] 168   b  B section DC to AC inverter.  
         [0154]    [0154] 170  Three phase alternating current utility power line.  
         [0155]    [0155] 172  Row A one through forty.  
         [0156]    [0156] 174  Generator control system.  
         [0157]    [0157] 176  Analog output card.  
         [0158]    [0158] 178  Analog output card.  
         [0159]    [0159] 180  I to P current to pneumatic transducer.  
         [0160]    [0160] 182  I to P current to pneumatic transducer.  
         [0161]    [0161] 184  Pressure tank.  
         [0162]    [0162] 186  Cooling fluid circulating pump.  
         [0163]    [0163] 188  Liquid to air heat exchanger.  
         [0164]    [0164] 190  Cooling fan.  
         [0165]    [0165] 192  Rotating inner drum support struts.  
         [0166]    [0166] 198  Set screws.  
         [0167]    [0167] 200  Shaft collar. 
         [0168]    While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.