By hvhipot 
HV Hipot Electric Co., Ltd. specializes in producing series resonance (also known as AC voltage withstand test device). Next, we will share the advantages of AC voltage withstand test device with you.
The series resonance can be roughly divided into several points. The series frequency conversion automatic resonance test device is mainly used for 10kV, 35kV, 110kV cross-linked rubber power cables, 66kV, 110kV combination electrical appliances (GIS) frequency conversion AC withstand voltage tests, and power frequency AC withstand voltage tests for hydraulic and thermal generators or power transformers. The basic principle is to use an adjustable (30-300Hz) series resonance test equipment to resonate with the capacitance of the test object to generate an AC test voltage.
Due to the large capacitance of cables, traditional power frequency test transformers are bulky, bulky, and difficult to obtain on-site power series resonances with high currents. Therefore, series resonant AC withstand voltage test equipment is generally used. Its input power capacity can be significantly reduced, weight can be reduced, and it is easy to use and transport. In the initial stage, induction type series resonant devices (50Hz) were commonly used, but they have disadvantages such as poor automation and high noise. Therefore, nowadays, frequency conversion resonance is mostly used, which can achieve higher quality factor (Q value), and has advantages such as automatic tuning, multiple protections, noise reduction, flexible combination methods, and light weight per piece.
I have learned a lot about the advantages of series resonant power supplies in voltage withstand testing of electrical equipment, but I would like to know what are the disadvantages of series resonant comparative testing transformers, or what electrical equipment cannot be subjected to voltage withstand testing using series resonant voltage withstand devices such as transformers, bushings, reactors, cables, capacitors, and transformers (including power frequency voltage withstand and induction voltage withstand)
The advantages of series resonance are light weight, low requirements for the power capacity of the test, large test capacity, and slightly lower price compared to test transformer cabinets of the same capacity. If the capacity is within 50kVA, it is recommended to use a test transformer. For small transformers, motors, and other equipment, it is required that the power supply be at the power frequency during testing, so using a test transformer is more convenient.
The variable frequency series resonant withstand voltage test device adopts the method of adjusting the power supply frequency to achieve resonance between the reactor and the tested capacitor, thereby obtaining high voltage and high current on the tested object. Due to its low power supply requirement, light equipment weight and small size, it has been widely praised and applied at home and abroad, and is a new method and trend of high voltage testing.