Many people wonder why a large number of pebbles are placed under transformers. Is it just for aesthetics? The answer lies in safety design, especially for oil-filled power equipment. Today, JINSHANMEN TECHNOLOGY CO., LTD explains the real functions of pebbles under transformers and their importance for safe operation.
I. What Are Oil Immersed Power Transformers?
First, we need to distinguish two common types: dry-type transformers and oil immersed power transformers. An oil immersed power transformer uses insulating oil as the main insulation and cooling medium. It features low cost, easy maintenance, excellent heat dissipation, and strong high-voltage insulation performance. However, the insulating oil is flammable, so fire and explosion protection is critical. This is also one of the core reasons why JINSHANMEN TECHNOLOGY CO., LTD pays special attention to safety design when producing oil immersed power transformers.
II. Pebbles: A Critical Safety Barrier for Oil Immersed Power Transformers
The area under an oil immersed power transformer is called an oil drainage pit or oil retention pit, connected to an emergency oil tank. Pebbles are not decorative-they are a mandatory safety structure required by fire protection regulations. For common equipment such as the 3 phase 100 kVA transformer, the pebble layout under the oil immersed power transformer is also an indispensable safety measure.
III. Main Functions of Pebbles Under Transformers
Oil Leakage Collection & Drainage: Pebbles absorb small oil leaks and guide the oil smoothly to the emergency oil tank, reducing potential risks. This is particularly important for equipment like the 3 phase 100 kVA transformer, which is widely used in daily scenarios.
Anti-Splash & Explosion Protection: In case of equipment failure or oil injection, pebbles can prevent oil splashing and reduce the risk of explosion, protecting the surrounding environment and equipment.
Fire Isolation & Firefighting Support: When a fire accident occurs, the pebble layer can isolate the flame, prevent the fire from spreading, and help with cooling and extinguishing, minimizing fire losses.
Auxiliary Cooling: Pebbles improve air circulation and provide auxiliary cooling for the transformer, ensuring stable operation even in high-temperature environments.
Electrical Insulation: Pebbles have good insulation performance, making it safer for inspection and maintenance personnel to work under the transformer.
Shock Absorption: Similar to railway ballast, pebbles can reduce vibration and stabilize the equipment, extending the service life of the oil immersed power transformer.
Weed Prevention: The pebble layer can effectively prevent weeds from growing and keep the foundation clean, avoiding the impact of weeds on equipment operation.
IV. Application Example: 3 Phase 100 kVA Transformer
A typical 3 phase 100 kVA transformer is widely used in distribution stations, factories, and commercial buildings. When installing an oil immersed power transformer such as a 3 phase 100 kVA transformer, the pebble layer must meet relevant standards: thickness not less than 250 mm, particle size 50–80 mm. This design ensures that even a commonly used 3 phase 100 kVA transformer can run safely and stably, which is also consistent with the safety standards followed by JINSHANMEN TECHNOLOGY CO., LTD in product design and installation guidance.
V. About JINSHANMEN TECHNOLOGY CO., LTD
JINSHANMEN TECHNOLOGY CO., LTD mainly produces oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, dry-type three-dimensional coiled power transformers, mining explosion-proof dry-type transformers, mining explosion-proof mobile substations, amorphous alloy power transformers, on load capacity regulating power transformers, locomotive dry-type transformers, as well as prefabricated substations, modular substations, wind energy box type substations, high and low voltage switchgear and other transmission and distribution equipment. We are committed to providing safe, reliable, and efficient power transmission and distribution solutions for global customers, and attaching great importance to the safety details of equipment operation, including the supporting safety design of oil immersed power transformers and 3 phase 100 kVA transformers.
VI. Fire Protection Regulations Requirements
Fire protection regulations have clear requirements for the pebble layout under oil immersed power transformers: 1. Outdoor single transformers and other oil-immersed electrical equipment with an oil volume of more than 1000kg shall be equipped with oil storage pits and oil drainage facilities. 2. The volume of the oil storage pit shall be determined according to 100% of the equipment oil volume or 20% of the equipment oil volume. When the oil storage pit is set according to 20% of the equipment oil volume, the bottom of the pit shall be equipped with an oil drainage pipe to discharge the accident oil into the accident oil storage pit. The inner diameter of the oil drainage pipe shall not be less than 100mm, and the oil shall be able to be discharged quickly in case of accident, and an iron grid filter shall be installed at the pipe orifice. 3. The oil storage pit shall be equipped with a grid with a clear distance not greater than 40mm, and pebbles shall be laid on the upper part of the grid with a thickness not less than 250mm and a particle size of 50–80mm. When a total accident oil pit is set, its volume shall be determined according to the total oil volume of the largest oil-filled electrical equipment. When a fixed water spray fire extinguishing device is installed, the volume of the total accident oil pit shall also consider the water spray volume and leave a certain margin.