Inside the Generator

Transcription

1 NHA Hydraulic Power Committee Fall Retreat & NWHA Technical Conference October 3, 2018 Walla Walla, WA Inside the Generator W. Howard Moudy Director of Operations National Electric Coil

2 The Classic Simplified View of a Generator HYDROGENERATOR applications do not bother with boiling the water! Instead, the water is poured directly on the turbine blades. 2

3 BASIC HYDRO TURBINE GENERATOR 3

4 Laminated Rotor Rim Hydrogenerator Typical 4

5 Hydro Generator Stator & Rotor Stator (Armature) High Voltage 13.8 kv common Stationary Rotor (Field) Low Voltage 125 to 375 vdc Varying Speeds 5

6 Stator Core Components Core Compression Plate Core Compression Fingers Core Building Bolts

7 Stator Core Lamination Style Core is made up of thousands of individual laminations Key Bar Slot (GE) Each one is coated with insulation Two main types of core lamination design: key bar and building bolt Building Bolt Slot (Westinghouse)

8 Stator Winding Components Bus Rings Coils Series & Group Connections Coil to Bus Connections 8

9 Stator Winding (coils or bars) multi-turn coils - one side installed in the bottom half of one slot and the other side installed in the top half of another slot (space between = throw) Bars or half Coils - one top and one bottom per slot 9

10 Multi-Turn Coils & Half Coils or Bars Diamond or Multi-Turn Coil inverted turn or twist transposition in the lower left on the bottom most turn Half-Coil or Bars Two bars (mirrored shapes) make up the complete coil when installed. 10

11 Insulated Connections Insulated connections are blocked and tied for longterm mechanical stability. 11

12 Hydro Generator Rotor Components Rotor Shaft Rotor Spider Rotor Rim 12

13 Shaft Coupling Coupling transfers torque through rotor shaft 13

14 Rotor Shaft Transmits Torque From Turbine Runner Typical Yield Strength» 60 to 75 KSI Primary Stress: Shear due to torsion Must also consider tension due to weight of all assemblies as it rotates Also consider stress concentration areas 14

15 Rotor Hub Shrink Fit to Shaft Keyway & Key Mated With Shaft to Lock Hub Into Position Greatest Stress Concentration is at the Keyway Sharp Corners Cracks Can Initiate at these areas of high stress concentration 15

16 Rotor Spider Transmit Torque From Shaft Hub to Field Winding Maintain Field Winding at Precise Airgap Reduce Overall Weight & Allow Ventilation Bending Stress (due to torsion and gravity) 16

17 Rotor Rim Supports & Constrains Field Poles During Rotation Characteristics: Either Integral with Spider or Separate Laminated Structure Has Radial (Bolt) Holes or Dovetails for Attaching Field Poles May Have Integral Brake Ring 17

18 Rotor Poles The number of poles depends on the machine design. The more poles on the rotor, the slower its rotation. 18

19 Rotor Pole Components 19

20 Field Pole Ground Insulation 20

21 Rotor Field Pole Components Copper Turns Insulated Pole Body Turns With Insulation 21

22 Insulated Rotor Poles 22

23 Radial Bolting Attachment Field Pole Attachment on Rotor Dovetail Keyway Attachment 23

24 Dovetail Key Pole Piece Attachment 24

25 Field Lead Designs Better designs have multiple laminations, and include a flexibility loop for growth due to temperature changes and rotational forces 25

26 Field Lead Designs 26

27 Field Lead Designs 27

28 Collector Ring Brush Holders Must have proper mechanical & electrical loading to achieve good wear rate Constant force recommended Amps/sq in Brushes wear faster if loading is lighter than required Proper filming never develops 28

29 Brush Holder 29

30 IGTC Forum Slide 30 10/23/2018

31 Inside the Generator Questions & Discussion W. Howard Moudy Director of Operations National Electric Coil (724)