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. 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 carries 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 and accurate test results.

First, prepare relevant data and information. For example, staff can prepare previous high-voltage test data and 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 and ensure that the air switch can meet 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 of the secondary current during operation.

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

Normally, 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 being tested and control it reasonably.

It should be specifically noted that if the voltage value is too small, during the voltage application, due to the influence of current leakage, the voltage value will continuously decrease, thereby 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 according to personal preferences.

Second, in the early stage of high-voltage testing, staff should conduct detailed analysis of the wiring for 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 test, staff should also enhance the reliability of the grounding of the metal casing of the test instruments. Furthermore, if a voltage regulator is needed during the test, staff should ensure 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 meter indications.

Finally, after completing the high-voltage test, 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 information. Therefore, when staff carefully analyze the test data, they must ensure the reliability and scientific nature of the analysis.

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

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