What is the Sequence of Transformer Factory Test (FAT) items?

Transformer factory test (FAT, Factory Acceptance Test) usually includes a series of key test items, the order of these items is carefully designed to ensure the accuracy of the test and the reliability of the equipment. The following is a common test item sequence and its reasons:

1. Visual Inspection

Order: First test
Reason: Ensures that the transformer has not sustained any physical damage during transportation or installation, such as deformation, damage, or missing components. This basic inspection helps avoid misjudgments in subsequent tests due to appearance issues.

2. DC Resistance Test

Order: Early test
Reason: Measures the DC resistance of the windings to verify the integrity of the windings and connections. Detecting any abnormalities early can prevent wasted time or further damage during more complex subsequent tests.

3. Turns Ratio Test

Order: After the DC resistance test
Reason: Verifies that the turns ratio of the transformer windings meets the design specifications. The turns ratio test typically uses a low-voltage AC signal, and if the prior DC resistance test is correct, this test further confirms the accuracy of the windings.

4. Insulation Resistance Test

Order: After the turns ratio test
Reason: Tests the insulation performance between the transformer windings and the ground. It ensures that the insulation between windings and from windings to the ground is intact, preparing for the high-voltage tests.

5. Tan Delta (Dissipation Factor) Test

Order: After the insulation resistance test
Reason: Evaluates the health of the transformer’s insulation system by assessing the performance and degradation level of the insulating medium. This test is usually performed before high-voltage tests to ensure the insulation system is in good condition.

6. Power Frequency Withstand Voltage Test

Order: After the Tan Delta test
Reason: Verifies the transformer’s ability to withstand high voltage. By applying a higher power frequency voltage, this test ensures that the transformer can operate under its rated voltage conditions without breakdown or insulation failure.

7. Induced Overvoltage Test

Order: After the withstand voltage test
Reason: Further verifies the transformer’s insulation strength under overvoltage conditions. By applying a higher frequency voltage, this test assesses the winding’s ability to withstand higher stress.

8. Partial Discharge Test

Order: After the withstand voltage test
Reason: Detects any partial discharge phenomena under high voltage, evaluating the overall quality of the insulation system and ensuring there are no potential insulation defects.

9. Temperature Rise Test

Order: After the withstand voltage and partial discharge tests
Reason: Verifies that the temperature rise of the transformer under full load conditions is within the allowable range, ensuring the effectiveness of the cooling system and preventing overheating issues during long-term operation.

10. No-load and Load Loss Test

Order: Final stage test
Reason: Measures the transformer’s no-load loss and load loss, assessing its efficiency. This test is usually performed after other performance tests are completed to ensure that the electrical characteristics of the transformer meet design requirements.

Summary

The sequence of these tests is designed to start with low-stress, non-destructive tests and gradually progress to higher-stress tests. By doing so, it ensures that the physical and electrical structure of the transformer remains intact before more complex and stringent tests are performed. This order helps prevent equipment damage or inaccurate test results due to improper testing sequence and ensures that all performance indicators of the transformer meet the required standards.

More Transformer Testers from Kingrun