Tap changer
![Tap changer inside a transformer.](/Images/godic/202502/15/CD242tapchanger2011a0754.jpg")
![A mechanical on-load tap changer(OLTC), also known as under- load tap changer (ULTC) design, changing back and forth between tap positions 2 and 3](/Images/godic/202502/15/Tap_changing_switch0754.gif")
![Drei einphasige Stufenschalter am Transformatordeckel montiert; die Regelableitung ist bereits angeschlossen](/Images/godic/202502/15/3_OLTC0754.jpg")
![Stufenschalter aus einem Leistungstransformator](/Images/godic/202502/15/DMM_72243_Stufenschalter_für_Leistungstransformator0754.jpg")
A tap changer is a connection point selection mechanism along a power transformer winding that allows a variable number of turns to be selected in discrete steps. A transformer with a variable turns ratio is produced, enabling stepped voltage regulation of the output. The tap selection may be made via an automatic or manual tap changer mechanism.