Analysis of Technical Difficulties in High-Voltage Testing of Power Transformers





Abstract

To further ensure the safety and reliability of power supply, it is crucial to conduct electrical high-voltage tests on power transformers. In this regard, after studying the main literature and related research materials on electrical high-voltage testing of power transformers, the author briefly discusses the test conditions required for such tests and analyzes the corresponding technical key points. ...

 Preliminary Preparations

As is well known, conducting electrical high-voltage tests on power transformers involves certain risks. Therefore, staff must make thorough preliminary preparations and adopt reasonable measures to prevent accidents, ensuring the safety of test personnel and obtaining reliable test results.

First, relevant data and information should be prepared. For example, staff can prepare previous high-voltage test data and achievement literature, as well as notes on issues and suggestions from pre-tests.

Second, staff should conduct safety inspections on the transformer equipment's own safety conditions and technical issues in advance, effectively improving the consistency between data and test fitting.

Third, prepare high-quality power supply equipment. From previous high-voltage tests, it is known that the power supply equipment used in tests is of large capacity. Therefore, staff should select appropriate power supply equipment based on test conditions, ensuring that the air switch meets the test requirements.

Additionally, since the secondary current of large-capacity power supply equipment is relatively high, the cross-section of the low-voltage side wires should be reasonably set to prevent excessive heating during application.

Fourth, use measuring instruments to check the laboratory temperature and humidity. If both exceed the reasonable range for testing, test personnel are prohibited from conducting electrical high-voltage tests.

Typically, since different equipment have different temperature requirements during testing, staff should read data based on the oil temperature around the windings.

Finally, analyze the nature of the high-voltage test. If it is a withstand voltage test, staff should comprehensively analyze the capacity of the step-up transformer based on the actual capacity of the transformer equipment being tested, and control it reasonably.

It should be specifically noted that if the voltage value is too small, due to the influence of current leakage during the voltage application, the voltage value will continuously decrease, affecting the accuracy of the final test data.

Key Points of the Test

First, during the wiring process, staff should strictly follow the pre-established execution plan and not handle wiring based on personal preferences.

Second, in the early stage of high-voltage testing, staff should conduct detailed analysis of the wiring composed of each part, ensuring the fairness and comprehensiveness of the inspection work, thereby ensuring the contact quality of the wiring to a certain extent.

Additionally, during the high-voltage testing phase, staff should also improve the reliability of the grounding of the metal casing of the test instruments as much as possible. Then, if a voltage regulator is needed during the test, staff should pay attention to whether it is in the "zero" state.

When using the voltage regulator, staff should rotate the handle evenly to increase the voltage slowly, while recording the operation and changes in instrument readings.

Finally, after the high-voltage test is completed, staff must adjust the voltage of the voltage regulator back to the initial "zero" state and cut off the power supply.

Data Analysis

As is well known, there are many types of electrical high-voltage tests for power transformers, and different tests yield different data. Therefore, when staff carefully analyze the test data, they must ensure the reliability and scientific nature of the analysis.

If the transformer equipment emits a "beeping" sound during the high-voltage test, staff need to analyze the characteristics of the sound.

For example, when gradually increasing the voltage to the test standard, if a "beeping" sound occurs but the instrument indicator does not change, staff can reduce the voltage to ensure the orderly progress of the test.