An investigation on the effectiveness of Scott transformer on harmonic reduction

Scott transformer is widely used in electric railway systems when there are two unbalanced single-phase loads. The transformer reduces unbalance current. This paper investigates that if Scott transformer can also reduce the harmonic current. Our study shows that when there are two harmonic-producing loads connected to each single-phase side of the transformer, the harmonics produced by loads will cancel out at the primary sides of the transformer and results in less harmonic current seen from the utility side. The amount of cancellation is affected by harmonic order and the size of loads.