Key Design Points: Skid-Mounted Base Structure & Transformer Oil Leak Prevention

I. Key Design Points of the Skid-Mounted Base Structure

1. Lightweight Design & Compliance Transport

Large-capacity transformers are prone to exceeding weight limits once filled with oil. The base design must incorporate compact, weight-reduction transformer technology, optimize the steel plate usage of structural members, and ensure the overall weight complies with road transport limits.

2. Mechanical Impact Resistance & Stiffness

Transportation over rough terrain, sudden braking, and the operation of upper-level equipment generate substantial dynamic loads. The base and enclosure must possess sufficient mechanical strength and stiffness, verified through finite element analysis (FEA), to prevent damage to internal precision equipment.

3. Vibration Isolation & Damping Design

To isolate the operational vibration of upper-level equipment from affecting lower-level devices such as microcomputer-based protection, vibration isolation pads shall be laid on the base mounting surface. The contact area must be precisely calculated based on the equipment's static and dynamic loads to prevent pad overloading and failure.

4. Slope Leveling, Anti-Corrosion & Drainage

The base of an oil-immersed transformer shall be designed with an appropriate slope (draining toward the conservator or oil pit), while dry-type transformers require leveling. In addition, the light-steel base requires anti-corrosion treatment, and the underside shall be elevated above the outdoor finished floor level with adequate drainage provisions.

II. Oil Leak Prevention Measures for Oil-Immersed Transformers

Outdoor Skid Mounted Switchgear

1. Structure & Material Optimization

• Upgrade sealing materials: Replace aging-prone rubber with high-temperature, oil-resistant, UV-resistant polymer or acrylate-based materials.
• Improve sealing structure: Apply a "figure-8" cross-section gasket at tank flange corners to form a double seal; replace vent plugs and oil sample valves with O-rings; machine the contact surface of the bushing vent plug into a smooth conical surface to enhance sealing reliability.

2. Standardized Installation & Fastening Practice

• Flange leak prevention: Tighten bolts strictly in a diagonal (crisscross) sequence to ensure uniform stress distribution; apply sealant or sealing gaskets as needed.
• Lifting damage prevention: Always use the manufacturer-designated lifting points; never lift by the bushings or radiators. When repositioning with jacks, place them on the dedicated jacking plate to avoid deforming the tank flange.
• Factory full inspection: The manufacturer shall perform complete trial assembly and leak testing to eliminate dimensional deviations and poor sealing at the source.

3. On-Line Repair Without Disassembly

Should leakage occur during service, polymer composite materials enable on-line repair (no welding, no oil draining):

• Surface preparation: Machine-grind the surface to expose bare metal and roughen it, then thoroughly degrease with a dedicated cleaning agent.
• Sealing & curing: Apply fast-curing oil-resistant material to seal the leakage point; after confirming no further leakage, apply high-strength protective material in layers and cure at ambient temperature.

III. Summary

Skid-mounted substation base design is a systematic engineering effort balancing lightweight construction, high strength, and vibration damping. Impact resistance must be verified through mechanical simulation, vibration isolation pad loading must be precisely calculated, and slope, anti-corrosion, and drainage designs must be fully implemented.

Oil leak prevention requires a full-lifecycle defense line: at the design stage, select high-performance polymer sealing materials and optimize the structure; at the installation stage, strictly control lifting and diagonal fastening procedures; and during operation, apply disassembly-free polymer composite on-line repair. Through these integrated measures, the absolute safety and long-term reliable operation of skid-mounted substations under frequent relocation and complex operating conditions can be effectively guaranteed.

Edited From：Noah