The SFQ series triple frequency transformer is designed according to the Chinese standard "GB311-61" and the "Regulations for Preventive Tests of Electrical Equipment", to meet the requirements of the power system for frequency-doubled induced overvoltage withstand test equipment for high-voltage instrument transformers. It is widely used for AC withstand voltage tests of series-excited voltage transformers at 35-220kV levels in the power system, to assess the main and auxiliary insulation strength of the transformer. It can also be used for induced tests on windings of motors and small transformers, and can serve as a 150Hz power supply for short-term operation.
The SFQ series triple frequency transformer adopts a three-core five-limb structure, selecting the working magnetic flux density of the iron core above the saturation magnetic density, so that the vector sum of the fundamental electromotive force (positive sequence vector) in the secondary winding connected in an open delta is zero, while the same-phase 150Hz third harmonic (zero sequence) appears at the two ends of the open delta.
