This product is designed in accordance with the People's Republic of China electric power industry standard DL/T848.4—2004 and the "Procedures for Preventive Tests of Electrical Equipment" issued by the former Ministry of Water Resources and Electric Power in January 1985, to meet the requirements of the power system for frequency-doubled induced voltage withstand test equipment for high-voltage voltage transformers. It is widely used for AC withstand voltage tests of series-excited voltage transformers in the 35-220kV class in power systems, to assess the main and insulation strength of the transformer, and can also be used for induced tests on windings of motors and small transformers; it can also serve as a 150Hz power source for short-term operation.
I. Brief Description:
This product utilizes the saturation characteristics of the magnetization curve of silicon steel sheet cores, and is a lightweight test device based on the principle of inducing a zero-sequence third harmonic electromotive force in the secondary winding connected in an open delta configuration of a three-phase transformer bank.
The lightweight triple-frequency generator produced by our factory can be provided as a complete set including control equipment and casing. This generator is one of the basic equipment for frequency-doubled induced high-voltage tests on series-excited high-voltage voltage transformers and small-capacity power transformers in power systems, power plants, substations, and power supply and distribution networks. It can also be used for frequency-doubled and voltage-doubled tests on various low-voltage electronic, instrument power transformers, and inductive coils of electrical appliances, and can also serve as a frequency-doubled power source with a power not exceeding 1 kilowatt for power supply or testing of certain special electrical equipment.
This product is a static frequency conversion device with low noise and small size, and can completely replace traditional frequency conversion units in high-voltage tests.
II. Basic Working Principle
Hot-selling product SBF-20/500 triple-frequency complete test deviceThree single-phase transformers have their primary windings connected in a Y configuration and secondary windings in an open delta configuration. When a three-phase 50Hz sinusoidal AC is applied to the primary side, the induced electromotive force on the secondary side is a flat-topped wave containing zero-sequence harmonics. The vector sum of the three-phase fundamental (positive-sequence) electromotive forces and the fifth harmonic (negative-sequence) electromotive forces equals zero, while the three-phase vector sum of the third harmonic (zero-sequence) electromotive forces adds in phase, so the third harmonic component in the zero-sequence harmonics is the largest.
Hot-selling product SBF-20/500 triple-frequency complete test deviceThe 150Hz (triple power frequency) induced voltage output from the secondary side of the open delta generator serves as the triple-frequency test power supply voltage. To obtain a larger 150Hz induced voltage output, the generator operates at a high working flux density, with the flux tending towards saturation (i.e., a larger over-excitation multiple), making the top of the induced voltage waveform on the secondary side flatter, and the amplitude of the decomposed 150Hz electromotive force larger. Therefore, the leakage reactance of the triple-frequency generator is relatively large and its variation is nonlinear, meaning the generator has a relatively high output impedance.
When the triple-frequency generator is loaded with a capacitive load (e.g., JCC—220 high-voltage series-excited voltage transformer), due to the low power factor, the generator's efficiency is relatively low, generally only about 20%. During loaded operation, a reactor can be connected to an idle winding of the test object on the secondary side of the generator for current compensation, to improve the power factor of the entire test circuit.
III. Equipment Structure and Technical Parameters
The transformer bank consists of three single-phase transformers, each with a core-type double-coil structure. The iron core is laminated with high-quality cold-rolled silicon steel sheets, and the coils are wound with high-strength polyester enameled copper wire and Class E insulation materials into cylindrical windings.
In addition to the transformer bank, the generator is equipped with a compensating reactor. The reactor has a similar structure to the single-phase transformer, but the iron core has an air gap (working air gap), and the coil parameters are different (no secondary winding).
The transformer bank can be assembled together according to user requirements, and the control box and reactor are of independent structures.
Product Aliases: Triple-frequency generator, triple-frequency induced voltage generator, triple-frequency power supply generator, triple-frequency test transformer device, triple-frequency induced withstand voltage generator, triple-frequency test transformer, triple-frequency tester, triple-frequency induced withstand voltage tester, voltage transformer frequency-doubled AC withstand voltage tester
IV. Technical Specifications of Triple-Frequency Generator
Input Voltage 380V 50Hz Sine wave
Output Voltage 250V- 1000V 150Hz Waveform distortion ≤5%
Output Capacity 3kVA, 5kVA, 10kVA, 20kVA, 50kVA
No-load operation time ≤5 minutes
Load operation time 40～60s
