Transformer Patrol Checks Must Not Be Neglected
In the power system, the transformer is a big “protagonist”. If the power system is a movie, then the transformer is the key role, responsible for converting electricity from high voltage to low voltage to ensure the normal operation of our lives. Therefore, the routine patrol check of the transformer cannot be sloppy. Let’s talk about the content and precautions of the electric transformer operational check.
The Purpose of Routine Patrols for Power Transformers
1. Evaluate the Operating Condition
The normal operation of the power transformer is a continuous and complex process. The operating status and quality of the transformer affect its performance and life. Therefore, long-term maintenance of the normal operation of the transformer is of particular importance to the power system. Routine patrol checks will help check whether the equipment is running stably, whether the hygiene is good, whether the equipment has leaks and damage, etc., to avoid safety risks and system downtime caused by abnormal equipment operation and failure.
2. Extend Equipment Life
By regularly inspecting the transformer, possible problems can be discovered in time, and quick and appropriate measures can be taken to repair them, which can extend the service life of the equipment, thereby avoiding high-cost equipment replacement.
3. Reduce Operational Risks
There may be some risks in conducting routine patrols of transformers in the power system. If there are no corresponding patrol records and emergency measures to quickly respond to unexpected situations, staff will not be able to guarantee their own safety. Therefore, long-term control of safety risks is essential for the success of the patrol work.
1. Wear a safety helmet, long-sleeved cotton work clothes and insulated shoes, insulated gloves, goggles, etc.
2. Carry tools: walkie-talkies, infrared thermometers, telescopes and other tools
3. Understand the on-site situation: understand the on-site weather conditions, equipment operation conditions and whether there are people working on the site, etc.
4. Dispatching patrol tasks: Use the mobile client PDA to dispatch routine patrol tasks.
5. Keep a safe distance: Keep a sufficient safe distance from live equipment, 1000kV not less than 8.5 meters, 500kV not less than 5 meters, 110kV not less than 1.5 meters, to prevent the risk of electric shock
6. Remain focused during the patrol, with at least two people monitoring each other. Avoid engaging in activities unrelated to the routine patrol work.
Routine Check Method: Look, Listen, Smell, and Touch & Measure
To ensure a comprehensive evaluation, a electric transformer routine patrol check should follow the four-step method:
Look: Visual Observation
Observe whether each part of the transformer is functioning properly.
1. Check that the surface of the casing porcelain bottle is clean, free of cracks and discharge marks: Because the voltage level and equipment of electric transformers are high, the operation and maintenance personnel generally use high-power telescopes to observe the casing porcelain bottle.
2. Check that the oil temperature and oil level are normal, and there is no oil leakage in all parts： the oil level of the oil pillow should correspond to the oil temperature and oil level curve provided by the manufacturer, and the temperature display of the transformer on-site thermometer and the monitoring system should be consistent, and the temperature error should generally not exceed 5℃
If the oil level is too low, the internal winding of the transformer may be exposed to the air, thereby affecting the heat dissipation effect of the transformer; if the oil level is too high, it may cause excessive pressure inside the transformer, and even cause abnormal conditions such as oil injection
3. Check that the gas relay glass is clean and the pressure relief valve is intact: the gas relay does not leak oil, and there is no internal gas accumulation, and the indicator rod of the pressure relief valve does not protrude and has no oil injection marks.
4. Check that the oil seal of the respirator is normal and the discoloration of the silica gel is normal: the discolored part should not exceed 2/3 of the total amount.
5. Check that the operation mode of the cooler meets the cooling requirements: the number of cooler groups should be enabled as required and reasonably distributed, the oil pump should operate normally, without other metal collision sounds, and no oil leakage
6. Routine patrol check of the connection parts of the transformer. The inspectors should check whether the connection parts of the transformer are tight and the connection is good, including the connection parts between the busbar and the bushing, the lead wire and the bushing, and the cable and the bushing. If problems such as loose connection parts or poor contact are found, they need to be handled in time to avoid local overheating caused by poor contact.
Listen: Sound Observation
Listen to the noise: Listen to the transformer for abnormal vibration and sound.
During normal operation, the transformer will emit a brisk “buzzing” sound. If you hear other abnormal sounds such as “squeaking” and “cracking”, there may be a short circuit inside the transformer, poor contact and other problems, and you need to take immediate measures to deal with it.
Focus on:
1. Listen for abnormal vibration and sound of the transformer body
2. Listen for the abnormal discharge sound of the transformer bushing and lead wire
3. Listen for an abnormal sound in the transformer air-cooled control box
Smell: Olfactory test
Sniff for unusual odors, particularly burnt smells.
Smell around the transformer body and cooling cabinets.
A burnt smell may indicate insulation overheating or electrical failure.
Touch & Measure: Tactile and Instrumental Inspection
Measure temperature: Measure whether the various parts of the transformer have abnormal heating.
Use an infrared thermometer to measure the temperature of the transformer body, bushing, cooler, air-cooled control box, etc., compare the three phases, and eliminate abnormal heating in time.
Special Patrol Items for Transformers
1. Windy weather: Check for flying threats and pay attention to the swing of the lead wire.
2. Rainy and snowy weather: Check whether the bushing is flashing or discharging.
3. Heavy snow weather: Check the snow accumulation and ice hanging, especially the connection between the top cover and the bushing, oil level gauge, thermometer, gas relay, and other parts.
4. Thunderstorm weather: Check the action of the arrester counter, bushing damage and discharge marks.
Post-Patrol Tasks
1. End the PDA patrol task: Verify that weather data, personnel details, patrol time, and conclusions recorded on the PDA are correct.
2. Fill in the PMS routine patrol: Ensure that the content filled in the PMS production system is accurate.
3. Sort out the defects found: enter the defects into the PMS production system and report to the relevant leaders and maintenance personnel
4. Make preventive measures and emergency plans: For serious and critical defects, comprehensively analyze the accidents that the defects may cause, formulate and implement preventive measures one by one, reduce power grid risks, and ensure the safe and stable operation of the UHV power grid.
Conclusion
In summary, power transformers are an important component of the power system, and routine patrol checks are an important means to maintain the overall operational stability. By performing regular checks based on “Look, Listen, Smell, and Touch & Measure,” potential issues can be identified early and resolved before failures occur. Before the routine patrol check, it is necessary to make precise and clear plans to fully understand the use and operation requirements of the equipment
