Transformer Maintenance
and Reliability
Aris Peña, CRL Senior Business Development
Manager
• Introduction
• Maintenance, aging
and testing
• Life-extension services
• Moisture reduction
• Reliability
• Conclusions
Content Overview
• Maintenance and reliability
are inseparable
• Influencing factors in
maintenance decisions
• Maintenance and monitoring
methods
Introduction
Maintenance, Aging and Testing
Corrective Maintenance
Reacting to problems when they occur
Preventive Maintenance
Routine repairs and maintenance
Predictive Maintenance
Utilizes trending data for optimal performance
Maintenance, Aging and Testing
Life of transformer = Life of paper
Oxidation attacks and
destroys paper
Life-extension Services
Acid level in oil: Data from 5,000+ transformers
Non-serviced group: Elevated acid levels
Average acid level: 0.11 mg KOH/g
Serviced group: Oil reclamation had been performed
Average acid level: 0.03 mg KOH/g
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0 10 20 30 40 50 60 70 80 90 100
Aci
d N
o. (m
g K
OH
/g)
Age (Years)
Acid Number as a function of Age(5,839 oil-filled transformers >500 kVA)
Non-serviced (1,675)
Serviced (4,164)
Life-extension Services
Acids attack insulating paper
Insulating paper loses tensile strength
The paper is irreversibly weakened
WHEN PAPER STRENGTH
DECREASES, THE RISK
OF FAILURE INCREASES
750x Magnification
Acid’s Effect on Paper: 0.05% Acid
750x Magnification
Acid’s Effect on Paper: 0.30% Acid
Life-extension Services
Study of 1,534 oil-filled transformers
Oil services include…
• Reclamation
• Moisture Reduction
• Oxidation Inhibitor Restoration
Life-extension Services
Moisture Reduction Passive online drying systems
Specs: 38,000 liters
Primary: 345 kVA
Secondary: 154 kVA
Duration: 12 months on 11 months off
Reliability Looking to the future
A contingency plan is essential
• Spare transformer
• Double-connected
substation
• Available rental
• Mobile substation
Reliability
Reliability
Reliability
Reliability
Reliability
DGA Monitoring
Reliability
• Degassing
• Removal of Acid and Sludge
• Moisture Reduction
• Processing | Equipment
• Fault Gas Monitoring
• Inspection and Repair
• Regasketing
• Full Electrical Testing
Reliability Actions Transformer PM and PdM Strategies
DGA Monitoring
• 1-gas monitor
Hydrogen present in most faults
• 8-gas monitor
Very effective solution
Higher-budget applications
• Intuitive data presentation
• Complete data management system
Data Management Transformer Dashboard®
Mechanical and
Maintenance
Fluid
Analysis
Health
Center
Monitor
Data
ET and IR
Data
Assessing risk is essential to securing a
reliable electrical system
Aging infrastructure demands an ambitious
maintenance strategy
Proactive steps contribute to valuable
uptime and life extension
Conclusions
Aris Peña Business Development
Representative
Thank you!