Can Transformers Operate Under Overload? The Basis Explained.
The overload capability of a transformer is an important reflection of its performance. This article will discuss the practical application of transformer overload operation based on the actual conditions of our STB transformers.
In transformer operation, exceeding the current specified on the nameplate is considered overload operation. Generally, long-term overload operation is not allowed. Overloading causes the temperature of the transformer to rise. The main factor determining the service life of a transformer is the aging of its insulation, and temperature plays a decisive role in this process. Research shows that for every 8°C increase in the operating temperature of the insulation, its service life is reduced by half.
However, most transformers have a certain overload capability, depending on their temperature rise conditions and insulation class. Temperature rise conditions are related to ambient temperature, the initial load before overload, the insulation and heat dissipation of the transformer, and the thermal time constant. If needed, the overload curves for dry-type transformers can be obtained from the manufacturer.
Most STB transformers are built to Class H standards, using Class H insulated enameled wire and a fully vacuum-insulated impregnation process compliant with CE certification. The maximum temperature rise can reach 180°C. Transformers produced according to this insulation class, such as those from Leilang, can operate under overload for a certain period without affecting their service life.
Reasonably utilizing the overload capacity of transformers can effectively improve power efficiency. As a transformer manufacturer, we offer the following recommendations:
- Due to the short-term overload capability of transformers, the rated capacity can be appropriately reduced when selecting a transformer. For example, for equipment with short-term impact overloads like rolling mills or welding machines, choose transformers with high temperature rise ratings to prevent breakdown. For scenarios with periodic peak loads, select transformers with high overload capability based on the average load capacity to avoid excessive capacity during low-load periods.
- In situations with multiple transformers in use, the overload capability can be leveraged to reduce backup capacity and the number of units, thereby cutting costs.
Shenzhen STB Electric Equipment Co., Ltd. is a wholly-owned subsidiary of Jishengchang Group. Established in 2004, the company operates its own industrial park and is a technologically advanced, well-established professional transformer manufacturer. It is one of the earliest companies in Shenzhen to enter the power transformer manufacturing sector. STB is the transformer brand under Shenzhen STB Electric Equipment Co., Ltd.
