A Tapping Range and Voltage Level Analysis Chart for Tap Changing Transformers

The operation of On Line Tap Changing (O.L.T.C.) transformers is subject to many power system variables and characteristics. These conditions include voltage variations, load fluctuations, transformer configurations and settings of tap changing relays. In this paper a graphical method is presented which simplifies analysis of O.L.T.C. transformer operation for variation in all the power system parameters. The graphical method eliminates the need for tedious repetitive calculations and allows the distribution engineer to readily determine transformer tapping requirements. The tapping range compatability of existing transformers can easily be determined in addition to the optimisation of system voltage float levels.