Safety Technical Measures and Precautions for Transformer Tests

Safety Technical Measures and Precautions for Transformer Tests

The personnel participating in the commissioning must be familiar with the performance, technical data and technical standards of the transformer. The commissioning personnel must be certified to work.
Personnel participating in the debugging must strictly follow the command instructions to proceed with the operation. Without receiving the command, they are strictly prohibited from operating on their own initiative.
Transformer tests should be carried out by two or more skilled technicians. The test supervisor should be an experienced person. One person operates and the other supervises. During the test, strict compliance with safety operation procedures must be ensured. Before the test, the test supervisor should give a detailed briefing to all test personnel on the precautions during the test.
Insulation tests and withstand voltage tests of electrical equipment should be carried out in dry and fine weather. They must not be conducted in bad weather such as low temperature, high temperature and rainy days. The ambient temperature during the tests should not be lower than 5 degrees Celsius and the relative humidity should not exceed 80%.

Before conducting any tests, an insulation resistance test must be performed using an insulation resistance meter. Only after confirming the insulation performance of the electrical equipment is good through non-destructive methods can other tests such as DC withstand voltage and AC withstand voltage tests be carried out.
The insulation resistance of the transformer should be measured both before and after the withstand voltage test to compare the insulation condition of the electrical equipment before and after the test.
When conducting electrical tests, the instruments and meters used should be selected based on the parameters to be adjusted and their precision requirements. The range and accuracy grade of the selected standard instruments and meters should both meet the adjustment requirements. The disconnection point between the high-voltage test pressurization section and other sections should have sufficient safety distance according to the test voltage.
When it is necessary to disconnect the equipment joints for testing, make marks before disassembling and check and verify the wiring after reconnecting.
The metal casing of the test equipment should be reliably grounded. The high-voltage leads should be as short as possible and, if necessary, firmly supported by insulating materials. The power switch of the test equipment should be a clearly openable double-pole isolating switch.
Barriers and fences should be set up at the test site, with “Stop, High Voltage Danger!” warning signs hung outward, and someone should be assigned to guard it.
Before applying pressure, carefully check the test wiring, the ratio and range of the meters, the zero position of the voltage regulator and the initial state of the instruments, all of which should be correct. Then notify the relevant personnel to leave the test equipment and obtain the permission of the test supervisor before applying pressure. During the pressure application process, there should be supervision. The high-voltage test personnel should be fully concentrated throughout the pressure application process, not chat with others, always be alert for any abnormal phenomena, and the operator should stand on an insulating mat.
When changing the wiring or completing the test, the test power supply should be disconnected first, the equipment discharged, and the high-voltage part of the voltage-raising equipment short-circuited and grounded.
For large-capacity test equipment without grounding, it should be discharged first before conducting tests. During high-voltage DC tests, the equipment should be discharged to ground several times at the end of each section or after the test is completed, and then short-circuited and grounded.
When the test is completed, the test personnel should remove the self-installed grounding short circuit line, inspect the tested equipment and clean up the site.
During the test process, keep accurate original records, and precisely record the temperature of the test equipment during the test and adjustment, as well as the temperature, humidity and other relevant data of the surrounding environment.