By hvhipot 
The main components of the series resonant device commonly used in the management of power enterprise departments are frequency and voltage regulation power supply, isolation transformer, reactor, excitation transformer, and capacitive voltage divider. The simultaneous series resonant connection method is composed of the reactor and capacitor of the test sample; The test sample is connected in parallel with a voltage divider, which is mainly used to measure the resonant voltage value on the test sample and provide an overvoltage protection signal
The variable frequency power supply used in series resonance is an indispensable protection device for the series resonance withstand voltage test. The detection device for series resonance withstand voltage test can provide more suitable experimental research voltage during the development of the test.
The frequency conversion technology is used to connect a resonant system in series, which adopts the principle of series resonance. The main equipment consists of a frequency conversion control power supply control box (operation console), excitation, transformer, reactor, and capacitive voltage divider. On the capacitive voltage divider, a rectifier silicon stack and a microampere meter are connected to complete the working DC withstand voltage performance test. Due to the excellent filtering characteristics of the system after resonance, the DC voltage generated by the system is better than that of ordinary test transformer rectifiers.
The frequency conversion technology is used in series with a resonant working frequency, where L is the inductance value of the reactor. If the following reactors are used in a series parallel system, the influence of mutual inductance should be considered; C is the sum of the test sample and the voltage divider capacitor. On site, we can use an electric bridge or dielectric loss meter for analysis, and actual measurements can be obtained. High voltage current I=2 π fCU, based on the electrical parameters of the sample and the factory withstand voltage test value, the on-site withstand voltage test voltage U can determine the active power PI=1.2 (P0P K), where P0 is the no-load loss of the excitation transformer and the rated active power loss of the reactor.
In the development process of frequency conversion series resonance test, the capacity of the excitation transformer should be greater than the active power P, and the input signal current on the primary side of the excitation transformer should be correspondingly reduced by reducing the transformation ratio of the excitation transformer as much as possible on the premise that the low output working voltage of the excitation transformer can meet different test design requirements. The market capacity of the experimental system power supply is S=P+P1, where P1 is the loss of the variable frequency control power supply technology itself. The operating current I1 of the power supply can be obtained by inputting and outputting a voltage of 380V from the power supply terminal. The rated working voltage and current of the reactor in the experiment should also be greater than the voltage and high voltage current of the testing system. When the reactor can be connected in series or parallel to meet different test design requirements, it is necessary to calculate and analyze that the voltage and current borne by each reactor do not exceed the limit.