Triple Frequency Power Generator, Triple Frequency Voltage Generator, Triple Frequency High Voltage Generator. This product is designed to meet the requirements of <>, <> and
The induced overvoltage test of transformers and instrument transformers is an important test to verify whether the product meets national standards. The longitudinal insulation induction test of winding interlayer, inter-turn, segment, and phase-to-phase insulation is an important item to verify whether the winding meets requirements. In order to increase the test voltage of the winding without causing over-saturation of the transformer or instrument transformer core, which would lead to excessive excitation current, the test frequency needs to be increased, typically to 100Hz-400Hz.
There are several methods to obtain a 100Hz-400Hz power supply, among which the most applicable ones are:
① Combination of three variable-frequency generators (100Hz-400Hz);
② Combination of three single-phase transformers (150Hz), and the most convenient is the second method.
The combination method of three single-phase transformers: the primary side is star-connected, and the secondary side is open-delta. When the core is not saturated, the main flux it produces must be a flat-topped wave. Since the flat-topped main flux contains a large component of third harmonic magnetic energy Φ3, and the frequency of the third harmonic flux f3=3f1, the main flux induces a third harmonic phase electromotive force.
Since the primary side is star-connected and the secondary side is open-delta connected, the core operates in a saturated state, and the no-load current I is a peaked wave. In addition to the fundamental component, it also contains higher harmonics. Among the higher harmonics, the amplitude of I is relatively large. Due to the open secondary, the three-phase fundamental components cancel each other out, leaving only the third harmonic output.
The entire machine's voltage output is achieved by tuning to resonance under a 150Hz power supply. When the voltage rises, a certain squealing sound during resonance is normal.
