125kVA Oil Immersed Transformer

NPC Electric manufactures three-phase oil-immersed transformers the strict quality control. The Progress Test of a 125kVA three-phase oil-immersed transformer is a series of intermediate tests performed during the transformer production process to ensure that the design requirements are met at each stage of manufacturing and to detect potential problems early. These tests are usually carried out in stages to ensure that the transformer gradually meets the quality standards during the production process. Mainly include:

1. Winding resistance test: During the winding production process, resistance measurement is performed to ensure that the winding is not open or short-circuited and to verify the correctness of the electrical connection.

2. Insulation resistance test: The insulation performance of the winding and other key parts is tested to ensure that there are no insulation defects during the production process to avoid electrical failures in the later stage.

3. Voltage ratio test: After the initial assembly, the voltage ratio test is performed to ensure that the input-output voltage ratio of the transformer meets the design specifications.

4. Preliminary load loss test: The load loss test is performed when the transformer is initially completed to evaluate its energy efficiency under different loads so that problems can be detected early.

5. Oil injection and oil quality inspection: After the transformer oil is injected, the quality and insulation performance of the oil are checked to ensure that the oil meets the standards and can effectively provide insulation protection.

6. Mechanical inspection: Check the transformer casing, connection terminals, and other structural parts to ensure that they are not damaged or missing during the assembly process.

7. Temperature Rise Test: The Temperature rise test is performed during the production process to simulate the working state of the transformer and ensure that no excessive temperature is generated under the design load.

Progress testing helps ensure that the transformer meets the design requirements at each stage of the production process, and timely detects and corrects problems to avoid major problems in the final factory acceptance test (FAT).

All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Ratio, Polarity, and Phase Relation
♦ Winding Resistance
♦ Impulse Tests
♦ On load Loss Test
♦ No Load Loss Test
♦ Leak Test
♦ DC Insulation Resistance Test
♦ Transformer Turns Ratio/TTR (All Tap Voltages)
♦ Impedance Voltage & Load Loss (Rated Voltage)
♦ Polarity, 1-Ph / Phase Relation, 3-Ph (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Induced Voltage
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
♦ Dielectric Withstand (Hipot)

Factory Acceptance Test (FAT) is the final verification step to ensure that 125kVA three-phase oil-immersed transformers meet all design, performance, and safety requirements before leaving the factory. This test is performed after the transformer is fully assembled and oil-filled, and usually includes the following:

1. Winding Resistance Test: Test the resistance value of the transformer winding to ensure that the electrical connection and insulation performance of the winding are good to avoid electrical failures.

2. Insulation Resistance Test: Check the insulation performance of each part of the transformer, especially the winding, casing, and grounding system, to ensure that it has good electrical insulation and prevent electrical leakage.

3. Load loss and no-load loss test: Evaluate the energy efficiency of the transformer under different load conditions to ensure that the energy loss is minimal when running at no load and load, and meet the standard requirements.

4. Short-circuit impedance test: Simulate short-circuit conditions to verify the electrical performance of the transformer when facing a short circuit, ensuring the safety and short-circuit resistance of the equipment.

5. Voltage ratio test: Check whether the voltage ratio between the high-voltage and low-voltage windings of the transformer meets the design requirements to ensure accurate voltage conversion.

6. Oil insulation strength test: Test the transformer's insulating oil to ensure that it has sufficient insulation strength, prevent leakage, and ensure long-term stable working performance.

7. Temperature rise test: Simulate the operating state of the transformer under rated load to confirm that it will not overheat during long-term use and maintain a safe working temperature.

8. Oil tank sealing check: Confirm that there is no leakage in the transformer's oil tank to ensure the integrity of the oil and the long-term reliability of the equipment.

The purpose of FAT is to verify whether the various performance of the transformer meets industry standards and customer requirements, and to ensure that the equipment can operate safely and reliably before leaving the factory.