You must know about withstand hipot testing

The series resonant device generates high voltage using the principle of electrical resonance. It is widely used for testing high-voltage power equipment, such as transformers and cables.

Components of a Series Resonant Circuit:

Inductance (L): The inductance in the series resonant device is typically made up of the test transformer and an inductor (usually a specialized coil). The magnetic field generated by the inductor produces a resonant frequency matching the capacitance.

Capacitance (C): The capacitance is usually provided by the device under test, such as the cable, motor, or transformer windings.

Resonant Frequency: The device adjusts the inductance and capacitance to reach a resonant state. When the circuit reaches resonance, the inductance and capacitance cancel each other out, producing a high voltage output.

How It Works

In a series resonant circuit, the inductance (L) and capacitance (C) interact to form a resonant state. When the power supply frequency matches the circuit's natural resonant frequency, the impedance is maximized, and the voltage is significantly amplified.

Resonant Voltage Amplification

The resonant circuit greatly amplifies the voltage. Due to resonance, the voltage increases, but the current remains low. This allows high voltage to be applied to the insulation of the device under test without overloading the power supply.

Adjusting Resonant Frequency

By changing the inductance or adjusting the input signal's frequency, the device can precisely control the output voltage. This enables the generation of higher voltage compared to traditional transformers for high-voltage testing.

Components of a Series Resonant Device

Low-Voltage Power Supply: Provides input voltage to the system.

Inductive Device: Usually consists of the test transformer and adjustable inductors, which adjust the frequency and generate the required high voltage.

Capacitor: The insulation of the device under test (e.g., cable or transformer winding) serves as the capacitor, determining the system's resonant frequency.

Measuring Equipment: Devices like voltmeters and frequency meters to measure test voltage and frequency.

Tests Performed Using a Series Resonant Device

Insulation Withstand Test for Power Cables: Used for testing high-voltage cables, especially for field withstand tests after installation.

Insulation Withstand Test for Transformers: High voltage is applied to test the insulation performance on both the high-voltage and low-voltage sides of the transformer, ensuring long-term insulation stability.

Insulation Test for Switching Equipment: Tests the insulation of circuit breakers, isolators, load switches, etc., to ensure safe operation under high voltage.

Partial Discharge Test for Electrical Equipment: High voltage is applied to check for partial discharge, which may indicate defects in the insulation.

Dielectric Loss (Tan Delta) Test for High-Voltage Equipment: Tan delta is measured during the test to assess the insulation condition. This helps detect insulation aging and identify potential issues early.