Combining your previous systematic understanding of power equipment such as series resonant devices
and online oil chromatography monitoring, the On-Load Tap Changer (OLTC), also known as the on-load voltage regulation device, is precisely the extremely sophisticated "intelligent gearbox" within the transformer, a massive entity.
If online oil chromatography monitoring is like conducting a "blood test" for the transformer, then the on-load tap changer is the core control component directly involved in the transformer's "daily driving." Its primary task is to adjust voltage in real-time and precisely by changing the turns ratio of the windings while the transformer remains in operation, energized, and under load, ensuring the continuity and stability of power supply to the grid.
Below is a detailed analysis of the core principles, technical types, and application status of this "precision gearbox":
⚙️ Core Working Principle: Millisecond-level "Make-Before-Break"
The most impressive aspect of the on-load tap changer is its ability to switch taps while carrying load currents up to thousands of amperes, without any interruption in the power supply. Its core technology lies in the "make-before-break" principle:
Transition circuit engagement: When switching taps, the switch uses transition resistors or vacuum interrupters to temporarily connect the next target tap position first.
Current transfer and interruption: Once the current has smoothly transferred to the new tap position, the original tap position is then disconnected.
Rapid completion: The entire switching process is typically completed within 10-20 milliseconds. Through this "seamless transition," it successfully avoids destructive arcs during the switching process and ensures absolute continuity of the load current.
