On Load Tap-Changer

Tap changers exist in two primary types, no load tap changers (NLTC) which must be de-energized before the turn ratio is adjusted and on load tap changers (OLTC) which may adjust their turn ratio during operation. The tap selection on any tap changer may be made via an automatic system, as is often the case for OLTC, or a manual tap changer, which is more common for NLTC. Additionally, tap changers are often placed on the high voltage (low current) transformer winding for easy access and to minimize the current load during operation.

For many power transformer applications, a supply interruption during a tap change is unacceptable, and the transformer is often fitted with a more expensive and complex on load tap changing (OLTC, sometimes Load Tap Changer, LTC) mechanism. On load tap changers may be generally classified as either mechanical, electronically assisted, or fully electronic.

Model Explanation

SY□Z(Z) - □/□-□L

                   S :  three-phase

                   Y :  on load

                   □:  voltage connection model

                   Z :  adopting resistance transit

                   Z :  direct switch

                   □:  rated current

                   □:  rated voltage

                   □:  number of voltage regulation grades

                   L :  online oil filter

Main Technical Data

Sample Model Parameters