By hvhipot 
The series resonance under HV Hipot Electric Co., Ltd. can help many power workers conduct various power tests more conveniently.What are the main components of a series resonance device?
A typical series resonance test system (also known as a variable frequency series resonance withstand voltage test system) is mainly composed of the following core components:
Its basic working principle is to adjust the power supply frequency so that the inductor L of the reactor in the circuit and the capacitance C of the test object enter into series resonance, thereby generating a high voltage across the test object that is much greater than the power supply voltage.
Main Components of a Series Resonance Device:
1. Variable Frequency Power Supply
Function: This is the “brain” and power series resonance of the entire system.
Role:
Converts mains frequency (50Hz) power into a sinusoidal wave output with adjustable frequency and voltage.
Provides control, protection, measurement, and display functions for the entire system.
Contains built-in protection units for over-voltage, over-current, over-temperature, flashover, etc.
Characteristics: Typically uses IGBT power devices and SPWM modulation technology to produce a pure, stable output waveform.
2. Excitation Transformer
Function: Steps up the output voltage from the variable frequency power supply to provide appropriate excitation voltage for the resonant circuit.
Role:
Electrical Isolation: Isolates the variable frequency power supply from the high-voltage circuit, ensuring safety and noise immunity.
Voltage Matching: Its output voltage needs to match the resonant voltage requirements of the reactor and the test object.
Characteristics: Usually has multiple taps to select the appropriate voltage ratio for different test requirements.
3. Reactor (High-Voltage Resonant Reactor)
Function: This is the core component that creates resonance, providing the inductance L.
Role: Forms a series resonant circuit with the capacitance C of the test object.
Characteristics:
Often, multiple reactors are used in series or parallel based on test voltage and current requirements to match different test object capacitances.
The reactors are adjustable (by changing series/parallel combinations or internal taps) to achieve the resonance point.
4. Capacitive Divider (High-Voltage Measurement System)
Function: Measures the high voltage on the test object and also acts as part of the resonant capacitance.
Role:
Measurement: Steps down the high voltage to a low-voltage signal via a precise division ratio, which is sent to the variable frequency power supply for display and control.
Feedback: Provides the sampling signal for the system’s over-voltage protection.
Characteristics: High measurement accuracy and good stability, making it a key component for ensuring accurate test voltage.
5. Compensation Capacitor (Optional, depending on the situation)
Function: Used when the capacitance of the test object is very small (e.g., short cable lengths or SF6 circuit breakers), causing the resonant frequency to be too high and exceed the device’s range.
Role: Connected in parallel with the test object to increase the total capacitance of the circuit, thereby lowering the resonant frequency so the device can operate within its effective frequency range.