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

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

Section 4.1 AC Generators and Generator Protection AC vs. DC

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

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

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

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

Direct – Gas (Hydrogen) Indirect – Water, Oil Section 4.1 AC Generators and Generator Protection Generator Cooling Direct – Gas (Hydrogen) Indirect – Water, Oil Liquid Hydrogen = -423.17º F

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

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

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

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

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

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

Section 4.1 AC Generators and Generator Protection Questions?