Comprehensive Guide to Transformer Installation Procedures and Precautions
As a core component of power systems, the quality of transformer installation directly impacts power supply stability. Even minor errors can result in local voltage fluctuations, while more severe issues may lead to equipment failures or even safety incidents. This guide provides a detailed explanation of the entire transformer installation process and key considerations from a professional perspective, presented in accessible language.
I. Pre-installation Preparation Work
1. Site Survey and Location Selection
The installation site must strictly comply with GB 50053 standards, and the location should prioritize dryness and ventilation. A case study showed that a transformer installed in a basement experienced rapid deterioration of insulation performance due to prolonged exposure to a humid environment, resulting in an electrical leakage fault within less than two years. Additionally, the groundwater level must be below the foundation base elevation to prevent groundwater erosion of the foundation. For oil-immersed transformers, the fire safety distance from residential buildings must be no less than 10 meters-a lesson learned from a tragic incident where a transformer in an old residential area caught fire due to its proximity to residential buildings, causing the fire to spread rapidly. Additionally, sufficient transportation channels must be reserved to accommodate large transformers, with channel widths typically needing to accommodate vehicles up to 5–8 meters in length.
2. Equipment Unpacking Inspection
In accordance with DL/T 572 regulations, unpacking inspection is akin to conducting a "health check" on the equipment. In addition to inspecting the transformer and its accessories for any damage or compromised seals, verifying the nameplate parameters is equally critical. There have been cases where construction teams failed to verify the parameters carefully and installed transformers with insufficient rated capacity, leading to frequent tripping during peak power consumption periods. Accessories must be accompanied by complete factory test reports to ensure that every component, such as thermometers and gas relays, meets performance standards; otherwise, safety hazards may be introduced.
3. Tool and Material Preparation
To do a good job, one must first have the right tools. Installation requires specialized tools such as a torque wrench (the tightening torque for M12 bolts must precisely reach 44 N·m; excessive torque may damage the bolts, while insufficient torque may result in inadequate fixation) and an insulation resistance tester. Regarding materials, silicone rubber insulating sleeves compliant with the GB/T 10581 standard can effectively resist environmental factors affecting insulation performance. Bolts and washers of different specifications must be precisely matched according to design requirements to avoid installation issues caused by mismatched specifications.
II. Installation Implementation Phase
1. Foundation Construction
Foundation construction is the foundation for the stable operation of the transformer. The concrete strength grade must not be lower than C20; insufficient strength may cause foundation settlement, affecting transformer operation. The horizontal error of the foundation surface must be controlled within 3 mm, and the center distance error of the embedded bolts must not exceed 2 mm. There have been cases where construction sites failed to meet the required foundation level, resulting in abnormal vibrations during transformer operation, necessitating rework. After construction is completed, curing must be performed, with a curing period of no less than 7 days to ensure the foundation reaches the designed strength.
2. Transformer Hoisting and Positioning
Hoisting operations are akin to a "high-altitude relay" and must be performed by certified professionals. Hoisting points must be selected based on the transformer's weight and center of gravity, and fragile components such as bushings must never be used to bear loads. During lifting, the tilt angle must not exceed 15°, as this may cause internal winding displacement. After positioning, precise adjustments are made using wedge-shaped shims to ensure the horizontal deviation is ≤1/1000. At a certain substation, improper operation during lifting caused the transformer to tilt, resulting in displacement of the internal oil reservoir and significant leakage of transformer oil, leading to severe losses.
3. Accessory Installation and Wiring
In accessory installation, bushing sealing is critical; inadequate sealing can allow moisture ingress, affecting insulation. After installation, radiators must undergo a 0.05 MPa air pressure seal test, with a pressure drop of ≤5% within 30 minutes to be considered合格. Protection device wiring must strictly follow the diagram. Incorrect phase sequence wiring can cause three-phase imbalance. Terminal contact resistance must be <50 μΩ, and heat-shrink tubing must be used for insulation. A certain factory once experienced a short circuit accident due to improper insulation treatment of the terminals, resulting in production line shutdown.
III. Post-Installation Testing and Protection
1. Electrical Testing
Electrical testing is the "litmus test" for evaluating installation quality.After installation, the radiator must undergo a 0.05 MPa air pressure seal test. It is considered qualified if the pressure drop is ≤5% within 30 minutes ; the three-phase imbalance rate of the DC resistance must be ≤2%. No-load testing detects core losses, while load testing verifies operational performance under rated load conditions. Any non-compliance must be immediately investigated and rectified.
2. On-Site Handling
After clearing debris from the site, apply 2–3 coats of anti-corrosion paint to the transformer housing in accordance with the HG/T 3668 standard, with a 24-hour interval between each coat. Set up a 1.7-meter-high barrier with gaps no larger than 10 centimeters to prevent small animals from entering; post prominent "High Voltage Danger" warning signs to ensure personnel safety.
IV. Installation Precautions
Installation personnel must strictly adhere to the DL 408 regulations. Work permits must be obtained for live-line operations, and a dedicated supervisor must be assigned. Bolt tightening must be performed using a torque wrench; manual tightening based on experience is strictly prohibited. After completing each critical step, conduct self-inspection and mutual inspection. For example, after foundation construction is completed, measure the foundation dimensions and take photographs for record-keeping. Detailed installation data, including equipment inspection results and test data, must be recorded and retained for at least 10 years to serve as important reference for future maintenance.