How is the temperature rise test done on a transformer?

As a core device for energy conversion and transmission in power systems, the temperature changes during transformer operation directly affect its insulation performance and lifespan. High temperatures can accelerate insulation degradation, potentially leading to serious faults such as short circuits and breakdowns. Therefore, temperature rise testing is a crucial step in evaluating the safety and reliability of transformers. With technological advancements, online winding temperature rise testers, with their high accuracy and efficiency, have become an essential tool for modern transformer temperature rise testing.  This article will provide a detailed explanation of transformer temperature rise testing and the applications of these instruments.

1. The Core Objectives of Transformer Temperature Rise Testing

The core objective of transformer temperature rise testing is to simulate actual operating conditions and measure the temperature rise of key components such as windings and core under rated load, to determine whether it meets design standards and industry regulations. Specifically, the objectives include: verifying the effectiveness of the transformer's cooling design to ensure that the temperature does not exceed the insulation material's temperature limit during prolonged full-load operation; assessing the relationship between the DC resistance of the windings and temperature to provide data support for safe transformer operation; and testing the temperature response of the transformer under special operating conditions such as sudden load changes to evaluate its dynamic stability.

2. Advantages and Components of a Live Winding Temperature Rise Tester

2.1 Key Advantages

Compared to traditional temperature rise measurement methods (such as thermocouple contact measurement), a live winding temperature rise tester offers significant advantages: It can measure winding temperature in real time without interrupting power, avoiding temperature fluctuations caused by power outages and ensuring data accuracy and continuity; it utilizes high-precision sensors and digital data acquisition technology to calculate temperature rise in real time using a dedicated formula, achieving far higher accuracy than traditional methods; it supports dual-channel simultaneous data acquisition, allowing monitoring of both primary and secondary winding thermal resistance values and calculating the corresponding temperature rise, thus greatly improving test efficiency; and it features automatic data storage, curve plotting, and report generation capabilities, facilitating analysis and traceability of test results.

3、Main Components

A temperature rise tester for energized windings typically consists of the following components: a signal acquisition module, including a high-precision platinum resistance sensor and a multi-range automatic switching module, which directly measures the resistance of the sample using the four-wire method; a data processing unit, which filters, amplifies, and converts the acquired signal to calculate the temperature rise; a display and control panel with a high-definition touchscreen, which displays the temperature curve, data list, and test parameters in real time and allows manual setting of test conditions; and communication interfaces, such as USB and RS232, for data export and remote control.

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