How Is an On-Load Tap-Changer (OLTC) Maintained?
Quick answer — OLTC maintenance follows the manufacturer cycle: inspect the contacts and the diverter for wear and arcing, test the oil (DGA for acetylene) and change it, check the drive and mechanism, measure the contact resistance, and verify the operation and the position. Many OLTCs are now sealed-for-life but still need periodic oil and DGA checks. A well-maintained OLTC prevents a leading cause of transformer faults.
How is an on-load tap changer maintained?
Routine checks
Verify the operation and the position, check the motor drive and mechanism, and inspect the contacts and diverter for wear and arc tracking.
Oil and DGA
Test the OLTC oil for acetylene and contamination; a rising acetylene indicates contact arcing, and the oil is changed per the schedule.
Contact and wear
Measure the contact resistance and follow the manufacturer contact-wear limits; check the drive and the spring/diverter condition and replace as specified.
References & standards
- IEC 60214 (tap-changers)
- IEEE C57.12.00
Related
Related manufacturers
Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp
Related components
Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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