Transformer test items vary depending on the type, application, and standards of the transformer. Generally, transformer tests are categorized into routine tests, type tests, and special tests. Below is a detailed classification of the tests and their content:
1. Routine Tests
These are essential tests conducted on every transformer before delivery to ensure proper functionality.
Measurement of winding resistance
Measures the DC resistance of transformer windings to check for short circuits or poor connections.
No-load test (no-load loss and current measurement)
Tests the transformer's performance when running without load, reflecting the core's properties.
Load test (load loss and impedance voltage measurement)
Measures losses and impedance voltage under full load conditions.
Insulation resistance test
Measures the insulation resistance between the windings and between windings and ground.
Dielectric loss factor (tan δ) test
Evaluates the dielectric loss of insulating materials to assess insulation performance.
Turns ratio test
Tests the voltage ratio between the primary and secondary windings to ensure the turns ratio is correct.
Polarity and phase group test
Checks the polarity and phase relationship of the transformer windings.
Withstand voltage test (power frequency withstand test)
Applies high voltage to the windings to test insulation strength.
2. Type Tests
These tests are performed on newly designed or specific models of transformers to verify their compliance with standards.
Lightning impulse test
Simulates lightning-induced voltage surges to verify the insulation system's resistance to surges.
Temperature rise test
Measures the temperature rise of the transformer under full load or overload conditions to test cooling performance.
Short-circuit test
Simulates operating conditions under a short circuit to test mechanical and thermal strength.
Noise level test
Measures the noise level during operation to ensure compliance with environmental requirements.
Partial discharge test
Detects partial discharge phenomena in the high-voltage insulation system.
3. Special Tests
These are conducted based on customer requirements or specific standard provisions.
Vibration test
Tests the transformer's ability to withstand vibrations during transportation or operation.
Environmental resistance test
Evaluates transformer performance under extreme environmental conditions such as humidity, salt spray, low or high temperature.
Online monitoring system calibration
Verifies the accuracy of online monitoring equipment (e.g., temperature, gas monitoring systems).
Leakage magnetic field test
Measures the intensity of leakage magnetic fields around the transformer.
Dissolved gas analysis (DGA)
Analyzes gases dissolved in transformer oil to detect potential faults.
Vacuum and pressure test
Tests the air-tightness and mechanical strength of the transformer tank.
Relevant Standards
Some commonly used international and national standards related to transformer testing include:
IEC 60076: "Power Transformers"
GB/T 6451: "Specifications and Requirements for Oil-Immersed Power Transformers"
GB/T 10228: "Specifications and Requirements for Dry-Type Power Transformers"
IEEE C57.12: "Standards for Distribution and Power Transformers"
If you need further clarification or specific details about any particular test, feel free to ask!
