A transformer oil water cooler is a heat exchanger used to remove heat from transformer insulating oil. During transformer operation, heat is generated by the windings, core, and electrical losses. The transformer oil absorbs this heat and carries it away from the hot internal parts.

In an oil water cooler, the hot transformer oil flows through one side of the heat exchanger, while cooling water flows through the other side. Heat transfers from the oil to the water through the heat transfer surface, and the cooled oil returns to the transformer tank or oil circulation system.

This type of cooler is commonly used in large power transformers, substation transformers, converter transformers, rectifier transformers, furnace transformers, and industrial transformer cooling systems. It is especially suitable for transformers with high heat load, limited installation space, or forced oil and forced water cooling systems.

The main purpose of a transformer oil water cooler is to keep the transformer oil temperature within a safe range, protect the winding insulation, slow oil aging, prevent overheating, and support reliable long-term transformer operation.