Comprehensive Guide to Transformer Factory Test Procedures

Transformers are essential components in power systems, responsible for functions such as voltage conversion, power distribution, and power source isolation. Before installation, transformers must undergo rigorous factory testing to confirm they meet production standards and performance requirements. The following outlines the main factory test procedures and their significance.

1. Overview

Factory testing ensures transformers are built to specification and capable of reliable operation under rated conditions. These tests verify critical performance indicators and compliance with user requirements, ensuring safety, efficiency, and durability in service.

2. Electrical Tests

1. Dielectric Loss and No-Load Test

   • Dielectric Loss Test:
     • Measures core and winding copper losses to confirm the soundness of the winding design and insulation.
     • Evaluates the quality of inter-turn insulation.
   • No-Load Test:
     • Determines no-load current, power factor, and no-load losses.
     • Verifies the efficiency of the transformer’s magnetic circuit and core design.

2. Starting Performance Test

   • Tests the starting current and startup time at rated voltage.
   • Ensures the transformer can handle normal operational conditions without failure.

3. Short-Circuit Test

   • Measures short-circuit current and voltage drop to evaluate:
     • The strength of windings and insulation under high-stress conditions.
     • The accuracy of rated capacity and the adequacy of safety protections.

3. Winding Insulation Resistance Test

• Assesses the overall insulation quality of transformer windings.
• Conducted under standard temperature and humidity conditions.
• Test results are recorded as benchmarks for future maintenance.

4. Transformer Oil Specification Inspection

The quality of the transformer oil is crucial to its insulation performance and longevity. The testing process includes:

1. Visual Inspection: Evaluates appearance, color, and odor of the oil.
2. Oil Quality Tests: Assess critical properties such as moisture content and compliance with local or international standards.
3. Impact: Poor oil quality can compromise insulation and shorten the service life of the transformer.

5. Appearance Inspection

Appearance inspection is the final step to identify mechanical or insulation damage caused during manufacture, transport, storage, or installation. This includes:

1. Plastic Components: Checking for warping, cracks, or reduced hardness.
2. Weld Seams: Inspecting for deformation, damage, or improper alignment.

This step ensures the transformer is free of visible defects and ready for reliable operation.

Conclusion

These comprehensive factory tests ensure transformers meet strict safety, performance, and reliability standards. By verifying electrical performance, insulation integrity, oil quality, and physical condition, engineers and procurement teams can be confident in the transformer's ability to handle a variety of loads in power systems. Proper testing mitigates risks and ensures transformers deliver consistent, efficient performance throughout their operational life.