Traditional power frequency test transformer: The principle is no different from ordinary transformers, directly generating the required power frequency high voltage through electromagnetic induction. Its output capacity (kVA) must be greater than or equal to the capacity of the test sample (=test voltage x test sample capacitance current).
Series resonance device: The principle of series resonance occurring at power frequency using inductance (L) and capacitance (C). During resonance, the voltage on the inductor and capacitor will be much higher than the input voltage (Q times, Q is the quality factor), and the power supply only needs to provide the active power loss in the entire circuit, thus greatly reducing the required input capacity.
The series resonance device offers several key advantages over traditional power frequency test transformers, making it the preferred choice for withstand voltage testing of large capacitive test objects (such as GIS, cables, generators, etc.):
1.Lighter weight and smaller size: It uses a modular reactor design, making the entire system much lighter and more compact than a traditional transformer of equivalent capacity. This makes it highly portable and ideal for field tests.
2.Much lower power supply requirements: By utilizing the resonance principle, the power supply only needs to provide the active power consumed in the circuit. The required capacity is only 1/10 to 1/50 of the test object's capacity, meaning a standard field power source or small generator is sufficient.
3.Excellent safety performance: If the test object breaks down, the resonance condition is immediately lost, and the short-circuit current automatically drops to 1/Q of the normal test current (where Q is the system's quality factor, typically 20-80). This effectively protects the test object from burning out and facilitates fault analysis.
4.High-quality output voltage: At resonance, the output is a pure power frequency sine wave free from harmonic distortion, ensuring accurate and reliable measurements that fully comply with standard requirements.
5.Wide application range: By adjusting inductance or frequency, a single set can adapt to test objects of different voltage levels and capacitances, offering strong versatility.