Triple Frequency Complete Test Device
This product is designed according to the People's Republic of China electric power industry standard DL/T848.4—2004 and the "Regulations 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 the frequency-doubling induced withstand voltage test equipment for high-voltage voltage transformers. It is widely used for AC withstand voltage tests of series-excited voltage transformers at 35-220kV levels 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 induces a zero-sequence third harmonic electromotive force in the secondary winding of a three-phase transformer bank connected in an open delta, making it a lightweight test device.
The lightweight triple frequency generator produced by our factory can be provided as a complete set including control equipment and chassis. This generator is one of the basic equipment for frequency-doubling 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-doubling and voltage-doubling tests on various low-voltage electronic, instrument power transformers, and inductor coils, and can serve as a frequency-doubling 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, which can completely replace traditional frequency conversion units in high voltage tests.
II. Basic Working Principle
Triple Frequency Complete Test Device The primary sides of three single-phase transformers are connected in a Y configuration, and the secondary sides are connected in an open delta. When a three-phase 50 Hz sinusoidal AC is connected 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 force and the fifth harmonic (negative sequence) electromotive force is zero, while the three-phase vector sum of the third harmonic (zero sequence) electromotive force adds in phase, so the third harmonic component in the zero-sequence harmonics is the largest.
Triple Frequency Complete Test Device The 150 Hz (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 150 Hz induced voltage output, the generator operates at a high working magnetic flux density, and the magnetic flux tends to saturate (i.e., a larger over-excitation multiple), making the top of the induced voltage waveform on the secondary side flatter, and the decomposed 150 Hz electromotive force amplitude is also larger. Therefore, the leakage reactance of the triple frequency generator is large and its variation is nonlinear, meaning the output impedance of the generator is relatively large.
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 efficiency of the generator is relatively low, generally only about 20%. When operating with a load, a reactor can be connected to a certain 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 made of high-quality cold-rolled silicon steel sheets, and the coils are made of high-strength polyester enameled copper wire and Class E insulating materials, wound into cylindrical windings.
In addition to the transformer bank, the generator is equipped with a compensation reactor. The structure of the reactor is similar to that of a 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, while the control box and reactor are 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-doubling 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
