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!