In the full lifecycle management of power equipment, the transformer, as one of the core assets, is of utmost importance in terms of its stability and safety. When an enterprise has a transformer that has been out of use for a long time due to production capacity adjustments, equipment upgrades, or other reasons, a comprehensive inspection and evaluation must be carried out before it is reactivated. Ignoring this step may lead to equipment failures, potential safety hazards, and even significant economic losses. The following are the 4 key items that must be checked before reactivating an idle transformer to ensure it can return to operation safely and efficiently.
Electrical Performance Testing: Verifying Whether the Basic Functions Meet the Standards
A transformer that has been out of use for a long time may experience aging of internal components or a decrease in insulation performance due to environmental factors such as humidity and temperature fluctuations. Before re-energizing, the following tests need to be carried out:
Winding Resistance Test: Detect whether there is poor contact in the windings due to oxidation or looseness.
Insulation Resistance Test: Use a megohmmeter to measure the insulation resistance between the windings, the core, and the casing to ensure it meets industry standards (such as IEEE 43).
Turn Ratio and No-Load Loss Test: Verify whether the voltage conversion efficiency of the transformer and the energy consumption in the no-load state are normal.
Tip: If partial discharge or abnormal insulation resistance is found, immediate drying treatment or replacement of damaged components is required.
Mechanical Structure Inspection: Eliminating the Risk of Physical Damage
During the idle period, the mechanical structure of the transformer may be damaged due to vibration, rust, or the intrusion of foreign objects. Focus on checking the following parts:
Appearance and Sealing: Check whether there are cracks, oil leakage, or rust on the casing, and whether the sealing gaskets are aged.
Connecting Components: Check whether the fastening bolts, tap changer contacts, etc. are loose or oxidized.
Cooling System: Confirm that the radiator, oil pump, and fan can operate normally to avoid overheating caused by poor heat dissipation.
Grounding System: Ensure that the grounding wire is reliably connected to prevent the risk of electric leakage.
Case: A factory failed to check the oxidation problem of the tap changer contacts, resulting in local overheating and burnout of the windings after the transformer was put back into operation.
Analysis of the Insulation Oil Status: Ensuring the Reliability of the Internal Medium
Transformer oil is the core medium for insulation and heat dissipation. Long-term standing may lead to deterioration of the oil quality:
Moisture Content Detection: Moisture will significantly reduce the insulation performance of the oil. It is necessary to determine the moisture content through the Karl Fischer method or oil chromatographic analysis.
Gas Content Test: An excessive content of dissolved gases (such as H₂, CH₄, C₂H₂) in the oil may indicate internal discharge or overheating faults.
Breakdown Voltage and Acid Value Test: Evaluate the aging degree of the oil. If the breakdown voltage is lower than 30kV or the acid value is > 0.1mg KOH/g, the oil needs to be filtered or replaced.
Suggestion: Combine oil chromatographic analysis with partial discharge detection to predict potential faults in advance.
Calibration of Ancillary Equipment and Protection Devices
The efficient operation of a transformer depends on the coordinated operation of supporting equipment. The following need to be focused on for inspection:
Bushings and Surge Arresters: Check whether there are cracks or dirt on the surface of the bushings, and whether the action characteristics of the surge arresters are normal.
Relay Protection Devices: Verify the sensitivity and reliability of protection functions such as overcurrent, differential, and gas protection.
Temperature and Oil Level Monitoring: Calibrate the thermometer and oil level gauge to ensure accurate real-time data.
Fire Protection System: Check whether the fire extinguishing devices (such as the oil-draining and nitrogen-injecting system) are in standby mode.
Note: Older transformers may not be equipped with digital monitoring functions. It is recommended to upgrade to smart sensors to improve operation and maintenance efficiency.
Conclusion: Scientific Evaluation Is the Premise for Safe Restart
Reactivating an idle transformer is not simply a matter of energizing it; it is a technical task that requires systematic evaluation. Enterprises should formulate targeted inspection plans based on the equipment's historical operation data, idle time, and environmental conditions. For complex problems (such as insulation oil deterioration or local winding discharge), it is recommended to entrust a professional institution for diagnosis and repair to ensure compliance with national grid standards (such as GB 1094.1) and industry specifications.
Call to Action:
If you need professional inspection services or technical support for idle transformers, you are welcome to contact our technical team. We provide a one-stop solution covering on-site inspection, oil analysis, and intelligent operation and maintenance to help you avoid risks and ensure the stable operation of the power system!
Through these 4 key inspections, enterprises can significantly reduce the risk of equipment restart, extend the service life of the transformer, and provide a reliable guarantee for production operations.