On-Load Tap Changer (OLTC)
A device changing transformer tap positions under load without interrupting supply for automatic voltage regulation.
An OLTC adjusts the turns ratio while energized and at full load. Unlike off-circuit tap changers (requiring de-energization), enables real-time voltage regulation without interruption.
Uses selector-diverter with transition impedance. Modern vacuum OLTCs eliminate oil contamination. Specs: 8-16 positions, 1.25%/2.5% steps, 300,000+ operations.
AVR monitors output voltage and commands OLTC to maintain band.
QDTB supplies premium OLTCs with vacuum or resistance transition, integrated with AVR. See LTC overview for details.
Related Products
Related Terms
Load Tap Changer (LTC)
A mechanism allowing transformer tap ratio changes while energized and under load for real-time voltage regulation.
Voltage Regulation
The change in secondary voltage from no-load to full-load as a percentage, indicating voltage stability.
Tap Changer
A device adjusting transformer turns ratio by connecting to different tap points on a winding.
Turns Ratio
The ratio of primary to secondary winding turns directly determining voltage transformation ratio.
More Terms Starting with “O”
Oil-Immersed Transformer
A transformer using mineral oil as insulation and cooling medium, most common for outdoor power and distribution.
Overexcitation
A condition where core flux exceeds design level due to excessive voltage or reduced frequency.
Oil Preservation System
Equipment preventing moisture and oxygen from entering transformer oil, including conservators and sealed tanks.
ONAN Cooling
The simplest transformer cooling method using natural oil circulation and natural air convection, requiring no pumps or fans.
More in “Components & Accessories”
Bushing
An insulated device allowing a conductor to pass through a grounded barrier while maintaining insulation integrity.
Busbar
A metallic strip conducting electricity within switchgear, transformers, and distribution equipment.
HV/LV Bushing
High-voltage and low-voltage insulated conduits for transformer winding connections through the grounded tank.
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