Technical Inspection Before Electric Transformer Installation

1. Winding-to-Ground Insulation Resistance Measurement

• Core Purpose: Detect overall moisture intrusion or insulation defects in the transformer.
• Key Significance: Prevents insulation breakdown caused by dampness or defects, avoiding short circuits between windings and the core.

2. Withstand Voltage Test

• Core Purpose: Verify if the transformer’s main insulation meets national standards under specified power frequency voltage.
• Key Significance: Ensures the insulation system can withstand rated voltage and transient overvoltage during operation, eliminating insulation failure risks.

3. Voltage Ratio Measurement & Connection Group Label Verification

• Core Purpose: Confirm the transformer achieves the expected voltage conversion effect, and the connection group matches the factory nameplate.
• Key Significance: Avoids voltage mismatch with the power grid or load equipment, preventing phase sequence errors that affect system integration.

4. No-Load Current & No-Load Loss Measurement

• Core Purpose: Check if no-load current and no-load loss comply with national standards and technical regulations.
• Key Significance: Reflects the quality of the transformer core (e.g., silicon steel sheet performance) and reduces unnecessary energy consumption during light-load operation.

5. Short-Circuit Impedance & Load Loss Measurement

• Core Purpose: Verify short-circuit impedance and load loss meet national standards or relevant regulations.
• Key Significance: Ensures the transformer can withstand short-circuit faults, limits fault current, and maintains efficient operation under rated load.

6. Winding Resistance Measurement

• Core Purpose: Inspect wire welding quality, tap changer contact (static and moving contacts), and three-phase DC resistance balance.
• Key Significance: Prevents local overheating caused by poor welding or contact, and avoids unbalanced current due to uneven three-phase resistance.

7. Transformer Oil Test

• Core Purpose: Evaluate oil quality by testing dielectric strength (pressure resistance), moisture content, acid value, and impurities.
• Key Operations: Compare test results with the factory test report; analyze the root cause if there are significant deviations.
• Key Significance: Ensures the oil maintains insulation and cooling functions, avoiding oil degradation-induced equipment failures.

8. Specialized Tests for Specific Scenarios

(1) Amorphous Alloy Iron Core Transformers

• Beyond visual inspection, additional insulation resistance measurement is required (targets the unique insulation structure of amorphous alloy cores).

(2) Transformers Protected by Fuses

• Supplemental tests: Verify fuse short-circuit capacity (ability to withstand fault current) and sensitivity (timely tripping to protect the transformer).

Key Compliance Notes

• All tests must adhere to GB/T national standards and CHH Power’s factory technical specifications.
• Test data must be recorded and archived for lifecycle maintenance reference.
• Abnormal test results require immediate troubleshooting (e.g., insulation defects, oil degradation) before the transformer is put into operation or continues service.