Pressure Relief Devices: Core Safety Protection for Oil-Filled & Dry-Type Transformers
Transformers serve as the core energy conversion hub of global power distribution systems, and their operational safety directly determines grid stability and continuous power supply capability. For oil-filled transformers, internal short circuits, insulation breakdown and aging faults will generate high-temperature electric arcs instantly, rapidly vaporizing internal insulating oil and producing massive high-pressure gas. This leads to a sharp surge in internal tank pressure. Without timely and effective pressure release, the transformer tank will deform, rupture, or even explode, causing flammable insulating oil leakage, severe fire accidents, and large-scale power outage losses.
As essential passive safety protection components, pressure relief devices are the final safety barrier for transformers against extreme fault failures. While they are standard configurations for all oil-immersed transformers, modern high-standard dry-type transformers also integrate optimized pressure relief and pressure monitoring structures. This has become a core safety upgrade direction for mainstream manufacturers of 100 kVA, 1600 kVA and 3000 kVA dry-type transformers, fully complying with global IEC 60076 power equipment safety standards.
Two Main Kinds of Pressure Relief Tools
According to transformer capacity, installation scenarios and safety grade requirements, pressure relief devices are divided into two mainstream types with differentiated structural designs, activation principles and applicable scenarios, realizing accurate safety protection for small, medium and large transformers.
1. Explosion-Proof Tube: Low-Cost Passive Protection for Small-Capacity Transformers
The explosion-proof tube is a trumpet-shaped pressure relief structure installed on the top of transformer oil tanks, featuring simple structure, zero energy consumption and low manufacturing cost. The tube outlet is sealed with a special thin-film pressure-sensitive material. Under normal operating conditions, the structure remains fully sealed to ensure the internal insulation environment of the transformer.
When internal faults occur and gas accumulation causes tank pressure to rise to the preset threshold of 50,000 Pa, the pressure-sensitive film breaks instantly. The high-pressure gas and oil mixture is quickly discharged outwards, releasing internal pressure in real time and effectively avoiding tank deformation, cracking and explosion risks.
This cost-effective protection solution is widely applied in small-capacity distribution transformers. Manufacturers of China 100 kVA dry-type transformers and small oil-immersed transformers commonly adopt this standardized pressure relief design. It perfectly adapts to low-load, stable operation scenarios such as office buildings, small commercial facilities and township conventional power distribution stations, covering basic daily safety protection demands.
2. Pressure Relief Valve: High-Precision Reusable Protection for Medium & Large Transformers
Different from disposable explosion-proof tubes, pressure relief valves are high-end, reusable safety components designed for medium and large-capacity transformers. With ultra-low opening pressure error, 2-millisecond ultra-fast response speed and cyclic reusable performance, they effectively avoid equipment downtime caused by protective device failure and are the preferred safety configuration for industrial and urban grid core transformers.
Structurally similar to boiler safety valves, the pressure relief valve is mounted on the top of the transformer tank, adopting an adjustable spring pressure control structure and dual-layer sealing disc design. Under normal operating conditions, the internal tank pressure acts on the small inner sealing ring of the valve disc, maintaining tight sealing and preventing dust and moisture from invading the tank.
Once internal fault pressure exceeds the preset spring tension, the valve disc lifts rapidly. The pressure instantly acts on the large outer sealing ring, driving the valve to fully open within milliseconds for rapid pressure discharge. The matched balance short pipe keeps the internal oil pressure balanced in normal state, ensuring stable long-term operation without leakage.
This high-precision and high-sensitivity design is widely used in high-standard large-capacity power equipment. Manufacturers of 3000 kVA dry-type transformers integrate optimized quick-response pressure relief valve structures into heavy-load transformer products. The classic China 1600 kVA dry-type transformer, widely deployed in urban central power stations, adopts a combined design of pressure relief valves and air-cooling systems, meeting strict safety and fire protection requirements for densely populated urban power distribution scenarios.
Conclusion: Safety Drives Better Technology
As power grids need to be more reliable, pressure relief devices are changing from "basic protection" to "active safety tools." For both manufacturers and users, understanding these systems is a must-whether for oil-filled or dry-type transformers.
If you're looking for trustworthy partners, China 100 kva dry type transformer manufacturers and 3000 kva dry type transformer manufacturers keep combining pressure relief expertise with the advantages of dry-type technology. They deliver safe, efficient products for all kinds of power needs.
About Us
Zhejiang Lvma Electric Co., Ltd. (LVMA) is a leading ISO 9001 certified manufacturer of distribution transformers, with 17 years of dedicated production experience. We specialize in high-quality oil-immersed and dry-type transformers, serving global markets including Europe, the Middle East, South America, Southeast Asia, and Africa.
Founded in 2018, LVMA has grown under the technical leadership of Mr. Ye Jinfei-a veteran with over 40 years in R&D who contributed to China's GB standard formulation. Our team holds more than 40 patents and is committed to innovation, quality, and safety in every product we deliver.
Through continuous development-from intelligent monitoring systems and green energy solutions to digital production-we have evolved from a traditional manufacturer into an intelligent, green electrical solutions provider, recognized worldwide for reliability and professional service.