elcid test of generator
DESCRIPTION
FOR FINDING OUT DEFECTS IN CORE OF GENERATORSTRANSCRIPT
EL CIDThe Modern Way to Test
Stator Core Insulation
Why Core Test?
Predictive Maintenance
Service/Repair
Manufacturing/QA
Requirement for Core Testing
Identify Repairable Damage
Reduce Unscheduled Outages
Schedule Necessary Repairs
Improve Efficiency through Reduced Thermal Stresses
Prolong Machine Life
Predictive Maintenance:
Requirement for Core Testing
Service/Repair:
Determine Fault Location
Assess Severity of Fault
Monitor and Verify Repairs
Requirement for Core Testing
Manufacturing/Quality Control:
Quality Assurance/Quality Control
Baseline Results for Machine Owner
Acceptance Testing
Common Causes of Damage
Relaxation of Core Clamping
Failure of Inter-laminar Insulation
Thermal Creeping
Loose Debris
Rotor Rub
Loose Coils, Wedges
Fault Current
Fault Current
Sample Core Damage
Accepted Test Methods
Large Power Supply Required
Safety Concerns with High Current
Expensive Thermal Sensing Equipment
1) High Power Ring Flux Test - the LOOP test
2) Electromagnetic Core Imperfection Detector - ELCID
Low Power Requirements
No Safety Concerns due to High Current
PROBLEMS WITH HIGH POWERED RING FLUX TEST
• AVAILABILITY OF POWER
• RUNNING HIGH CURRENT/HIGH VOLTAGE CABLES AND MECHANICAL
STRESSES
• TIME REQUIRED FOR TEST
• MANPOWER REQUIRED FOR TEST
• SAFETY PRECAUTIONS AND PROCEDURES
• NO ACCESS TO STATOR BORE WHILE THIS TEST IN PROGRESS
• COOLING OR HEATING TIME BETWEEN TEST/REPAIR/ TEST ETC.
• POSSIBILITY OF INCREASED DAMAGE DUE TO TESTS
- NO COOLING ETC. -
• PHYSICALLY SMALL BUT SERIOUS FAULTS NOT ALWAYS DETECTABLE
IF DEEP SEATED OR BENEATH WINDINGS
THE SOLUTION - ELCID•INITIALLY DEVISED BY CEGB - LOW EXCITATION POWER REQUIREMENTS
•FAST - EASILY SET UP
•LOW MAN POWER REQUIREMENTS
•NO SAFETY HAZARDS OR COMPLICATIONS
•INSTANT TEST RESULTS
•STATOR CAN BE REPAIRED SIMULTANEOUSLY WITH FURTHER TESTING - NO NEED TO COOL DOWN OR DISMANTLE TEST GEAR
•POWER LEVEL TOO LOW TO CASE FURTHER DAMAGE
•FAULTS NOT OBSCURED BY WINDINGS
•SPEED ALLOWS FAST TESTS TO BE CARRIED OUT BEFORE AND AFTER OTHER MAINTENANCE WORK (E.G. WEDGING)
•AUTOMATIC PERMANENT RECORDS FOR FAULT H ISTORY MONITORING OR QA PROCEDURES
•EQUIPMENT VERY PORTABLE
Typical Hydrogenerator Excitation System
Typical Turbo generator Excitation System
System Configuration
Positioning the Chattock
Interpretation of Data
Required Excitation Levels
Loop Test
100% +
ELCID
4%(of rated flux density)
System Configuration
Measuring Fault Current with a Chattock Potentiometer
Digital ELCID - Model 601
Method of Scanning
Method of Scanning
Business Justifications
Improved Machine Efficiency
Increased Reliability
Reduced Outages
Reduced Power Consumption during Test
Alternator with Rotating Field
Functional Layout
Digital Processor
Reference Coil Chattock Coil DistanceTransducer
X-Y Chart Recorder
Signal Conditioning
A/D Converter
RS-232 Interface
Distance Encoder
D/A Converter
Portable Computer
Advantages
Low Excitation Power - 4% Fast - Easy to Setup Low Manpower Requirements Significant Reduction in Safety Hazards Instant Interpretation of Test Results Minimal Risk of Further Damage Ability to Re-Test During Maintenance
Cycle Permanent Data Storage Portability
Suggested Usage
Predictive Maintenance:
Manufacturing/Quality Control:
Service/Repair: Beginning of the Maintenance Cycle During Repair Procedures After Completion of Work
Throughout Stacking Process QA for Final Acceptance Acceptance Baseline Test for End-User
Global Scan at available planned intervals
Excitation & Induced Voltages Across Laminations
Flux produced by Excitation
Voltage induced across one pair of laminations
Voltage induced across damaged laminations
Voltage induced along complete core length
Excitation, Fault Volts and Fault Current
Flux produced by Excitation
Voltage induced across damaged laminations
Fault CurrentPhase angle that Fault Current lags Fault Voltage
Excitation, Fault Volts, Fault Current and Quad Fault Current
Flux produced by Excitation
Voltage induced across damaged laminations
Fault Current
Quadrature component of Fault Current
Watts dissipated due to fault
Excitation, Fault Volts and Fault Currents 1 & 2
Flux produced by Excitation
Voltage induced across damaged laminations
Phase Angle for If2
Fault Current 1 Phase Angle for If1
Fault Current 2
Quadrature Fault Current 1
Quadrature Fault Current 2
Sample Fault Indication (Turbo)