Frequently Asked Questions
Technical insights and troubleshooting guides for transformer maintenance and voltage regulation systems.
An On-Load Tap Changer (OLTC) is a critical component of a power transformer that allows for voltage regulation without interrupting the power supply. It adjusts the transformer's turns ratio under load, ensuring a stable secondary voltage despite fluctuations in the primary voltage or load changes. This is essential for maintaining grid stability and protecting sensitive industrial equipment.
OLTC diverter switch oil degrades much faster than main tank oil due to arcing during switching. Generally, oil should be tested every 6-12 months. High-vacuum filtration or full replacement is recommended every 5,000 to 10,000 operations, or at minimum every 24 months, depending on the load profile and environmental conditions.
Signs of a failing transition resistor include unusually slow tap changes, abnormal noise or vibration during switching, high combustible gas levels (especially ethylene and acetylene) in DGA testing, and increased contact resistance when measured offline. If a transition resistor fails completely, it can cause catastrophic arcing inside the diverter switch compartment.
Yes, our modern RTCC panels are designed for seamless integration. We support industry-standard protocols including Modbus RTU/TCP, DNP3, and IEC 61850. We can retrofit older substations by upgrading the control panel and providing the necessary communication interfaces to your Energy Management System (EMS).
In a traditional resistor-type OLTC, the selector switch pre-selects the physical tap connection on the transformer winding without carrying load current. The diverter switch is the rapid-acting mechanism that actually transfers the load current from the old tap to the new tap, using transition resistors to bridge the gap without interrupting power.
Contact resistance measurement (CRM) verifies the integrity of the electrical connections inside the tap changer. High resistance indicates pitted contacts, carbon buildup, or weakened spring pressure. Identifying and replacing these worn contacts early prevents overheating and eventual failure of the tap changer under heavy load.
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