1. Engineering Technology Division
Power Plant Construction and QA/QC
Section 4.1 AC Generators and Generator Protection

2. Generators are the production point for electricity
Section 4.1 AC Generators and Generator Protection
Overview
Generators are the production point for electricity
Both Alternating and Direct Current is generated
Alternating Current travels both directions
Direct Current travels in only one direction
DC was developed first in the mid – 1870
DC has a limited travel distance – requires high current
AC has “no” distance limits in comparison
Prime movers are needed to turn generators
Prime movers are geared to match generator design
99.2% of the power generated today is AC

3. Section 4.1 AC Generators and Generator Protection
AC vs. DC

4. Generator Types - Synchronous
Section 4.1 AC Generators and Generator Protection
Generator Types - Synchronous
3 Phase AC 2 Pole, 3 Coil

5. Generator Types - Synchronous
Section 4.1 AC Generators and Generator Protection
Generator Types - Synchronous
Synchronous Generators are common for Power Plants
Stator
Exciter
Rotor
Voltage and current from Stator

6. Generator Types - Synchronous
Section 4.1 AC Generators and Generator Protection
Generator Types - Synchronous
Stator
Rotor

7. Generator Types - Induction
Section 4.1 AC Generators and Generator Protection
Generator Types - Induction
Voltage and current from Rotor

8. Direct – Gas (Hydrogen) Indirect – Water, Oil
Section 4.1 AC Generators and Generator Protection
Generator Cooling
Direct – Gas (Hydrogen) Indirect – Water, Oil
Liquid Hydrogen = º F

9. Generator Rating Section 4.1 AC Generators and Generator Protection
Over Excitation Under

10. Exciters Section 4.1 AC Generators and Generator Protection
DC Generator, Rotating AC, Brushless

11. Exciters Section 4.1 AC Generators and Generator Protection
DC Generator, Rotating AC, Brushless

12. Exciters Section 4.1 AC Generators and Generator Protection
DC Generator, Rotating AC, Brushless

13. Generator Synchronizing
Section 4.1 AC Generators and Generator Protection
Generator Synchronizing
Generator 1
Generator 2
Speed Control
Speed Control
Breaker Switch
Breaker Switch
Exciter Control
Exciter Control

14. Differential Current – fault between phases
Section 4.1 AC Generators and Generator Protection
Generator Protection
Differential Current – fault between phases
Voltage Regulation – generator control
Stator Overcurrent – high operating levels
Negative Sequence Current - phase imbalance
Stator Ground Fault – stator ground
Field Ground – rotor ground
Loss of Excitation Protection – synchronization loss
Motoring protection – loss of prime mover

15. Section 4.1 AC Generators and Generator Protection
Questions?