Description

Transformer Testing and Commissioning Transformer testing and commissioning ensure that a transformer is installed correctly, operates safely, and performs according to specifications before being put into service. 1. Visual Inspection Check for physical damages: Inspect bushings, tap changers, oil leaks, signs of corrosion or rust. Verify connections: Ensure all cable and grounding connections are secure and according to the wiring diagram. Check oil level: Confirm oil levels are within specified limits. 2. Pre-energization Tests These tests are done before applying voltage to the transformer and include: Insulation Resistance Test (Megger Test): Measures the insulation resistance between the transformer windings and earth to check insulation quality. Polarity and Phase Relation Test: Ensures proper connection of transformer windings and phase correctness. Turns Ratio Test: Determines the ratio of primary to secondary windings to verify transformer ratio and detect winding faults. Winding Resistance Test: Checks the condition of the winding and detects open circuits or shorted turns. Dielectric/High Voltage Test: Verifies the transformer's ability to withstand high voltages without breakdown. Oil Tests: Tests such as dielectric breakdown voltage, moisture content, and dissolved gas analysis (DGA) to assess oil insulation quality. 3. Energization and Functional Tests Once pre-tests are satisfactory, the transformer is energized and these tests are conducted: No-Load Loss and Current Test: Measures iron losses and no-load current to verify efficiency. Load Loss and Impedance Voltage Test: Determines copper losses and impedance to check performance under load. Temperature Rise Test: Assesses the transformer's ability to handle rated load without overheating. Protection System Check: Tests relay settings, Buchholz relay, pressure relief devices, and other protection mechanisms. Tap Changer Operation Test: Verifies the operation and settings of on-load or off-load tap changers. 4. Commissioning Synchronization: For transformers connected in parallel, synchronization with the system is performed. Final Inspection: Ensure all test results are within manufacturer and design specification limits. Documentation: Compile test results, observations, and commissioning reports. Handover: Officially hand over the transformer to the operations team.