The on-site acceptance test (SAT) of power transformers is a crucial step to ensure that the equipment meets the performance standards and operates safely and reliably after installation. The test covers functional verification, performance assessment, and safety inspection, and it needs to be carried out in conjunction with professional testing equipment and standardized procedures. The on-site acceptance test should be carried out in accordance with relevant standards (such as IEC, GB series), and the key items include below:
1. Insulation resistance test: Use an ohmmeter to measure the insulation resistance between windings and between windings and ground, to assess the integrity of the insulation. On the system, and prevent insulation damage caused by transportation or installation. You can choouse Huayi brand DMG2671F, BC2030 10KV insulation resistance tester.
2. Dielectric loss test: Use a dielectric loss tester to measure the tangent value of the dielectric loss angle (tanδ) of the insulation medium, to determine the degree of insulation aging or moisture absorption. The HUAYI brand JS-V/JS-R tan delta tester is the idea equipment to do dielectric loss test.
3. Ratio test: Use a ratio bridge to confirm whether the actual ratio of the transformer deviates from the designed value within the allowable range (usually ≤ ±0.5%). The Huayi brand BBC-HI TTR meter can conduct the ratio test.
4. DC resistance test: Measure the DC resistance of each phase winding to ensure that the three-phase imbalance meets the standard (for transformers above 1600 kVA, the imbalance should be ≤ 2%). The HUAYI brand ZZS-10A and ZZS-20A 3-phase DC resistance tester can meet the requirements.
5. Load and temperature rise test. Simulate the rated load condition, monitor whether the winding temperature rise meets the design requirements (for oil-immersed transformers, the temperature rise limit is 65K), and monitor in real time with equipment such as infrared thermometers.
6. Protection function linkage test. Verify the action logic of protection devices, such as gas relays and pressure release valves, to ensure that the power supply can be quickly cut off in the event of a fault.