Introduction to Testing and Maintenance Procedures for High-Voltage Test Transformers

发布时间：2022-01-12

The high‑voltage testing transformer is a fundamental piece of test equipment used by power plants, power supply bureaus, research institutions, and many other users to perform AC withstand voltage tests. It has been certified in accordance with national quality‑supervision standards and is employed to conduct insulation‑strength tests at specified voltages on various electrical products, electrical components, insulating materials, and more—thereby assessing the insulation performance of the tested items, identifying insulation defects, and evaluating their ability to withstand overvoltages.

After the power-frequency supply is connected to the control box (or console), the voltage is adjusted by an autotransformer and then applied to the primary winding. Based on the principle of electromagnetic induction, a power-frequency high voltage is induced in the secondary winding (the high-voltage side, which typically has a higher number of turns). This power-frequency high voltage is rectified by a high-voltage silicon stack and filtered by capacitors, yielding a DC high voltage whose peak value can reach 1.4 times the effective value of the power-frequency high voltage.

Next, let us examine the testing and maintenance procedures for high‑voltage test transformers: Oil sample analysis—covering dielectric strength, impurities, and other performance parameters—should be conducted every three years; however, for transformers operating continuously at full or overload capacity, the interval may be shortened. The insulation resistance of both high‑ and low‑voltage windings shall not fall below 10 MΩ. At a given temperature, the deviation among the three‑phase DC resistance values should not exceed 2%, nor should it differ by more than 2% compared with the previous measurement. The working grounding resistance must be measured once every two years. The frequency of outage‑based cleaning and inspection depends on the surrounding environment and load conditions, typically ranging from once every six months to once a year. Key tasks include addressing defects identified during routine inspections, cleaning the porcelain bushing housings, replacing cracked or aged rubber gaskets, tightening and inspecting connection points, topping up oil if necessary, and checking and replacing the desiccant in the breather.

A brief overview of the operating principle of handheld partial discharge detectors!

Let’s take a closer look at the system principles of partial discharge detectors.

A brief overview of the operating principle of handheld partial discharge detectors!

Let’s take a closer look at the system principles of partial discharge detectors.