Transformer Oil Cooling

Air Cooled

(Type FOFA, FOA or OFP)

Unifin’s Forced Oil – Forced Air Transformer Oil Coolers can be standard units or custom designed to dissipate a particular heat load or meet a specific application requirement. Standard cooler lines are pre-engineered around industry standards with numerous custom features available as options.

Heat Sink

The Heatsink is a self-contained cooling system complete with cooler, pumps, valves, expansion tank and all other components required to provide auxiliary cooling to an overheating transformer.

This series of Auxiliary coolers have been specifically designed to augment the cooling capacity of transformers in service. With recent years being some of the hottest on record, and with the high demand for electricity during the hottest part of the summer months, keeping transformers operating at capacity has become crucial to all utilities.

The portable Heatsink Auxiliary Transformer Cooler will allow increased overload, extend life and save money. When you install a Heatsink unit, you can eliminate present and future overload problems by reducing the temperature of the dielectric oil in the transformer. Heatsink Auxiliary Transformer Coolers can be installed quickly with little modification to the transformer. Using optional quick connect hoses, and the optional trailer, your Heatsink transformer cooler can be transferred easily from one overloaded substation to another.

Water Cooled

(Type OFW / ONW)

We provide water to transformer oil coolers with the unique leak detector feature that not only identifies a leak but captures and isolates the leaking fluid so the oil and water do not mix .

Forced Oil Flow (OFW)

An OFW Cooler is a forced-oil-forced water transformer oil cooler. This describes that an external pump is used to circulate the oil through both the transformer and the cooler to assist in cooling the oil. The OFW cooler may be mounted in either a horizontal or vertical orientation on the side of the transformer. This design is available in a standard or Leak Detector design – both include double tubesheets.

Natural Oil Flow (ONW)

ONW Coolers are a shell & tube heat exchanger with natural oil convection on the shell side and water through the tube – no pump is used to move the oil through the transformer or cooler. A natural flow of oil is set up through the density change that occurs as the oil is heated in the transformer then cooled in the external cooler.

The ONW cooler is available with the exclusive Unifin leak detector feature which allows immediate detection of any water leaks before the safety of the transformer is compromised due to water penetrating into the oil and it protects the environment by preventing the oil from entering the water. Fifteen standard sizes are available in both conventional or leak detector design, both incorporating double tubesheet construction.

Standard Features:

• Heavy Duty class 30 cast iron is used for the pump casing, motor enclosure and impeller to provide long life.
• Pump and motor units are pressure tested to 50 psig to establish the integrity of the complete unit.
• Motor windings Hi-Pot tested for 60 seconds at (2x voltage + 1000), to ensure the electrical integrity and continuity.
• Impellers designed to permit thermosyphon flow (allows natural convection even when the pump is shut off).
• The pumps continuous duty operating temperatures are -40ºc (-40°F) to + 100°c (+212°F).
• Winding resistances of the motor are taken before and after the pump is built, to ensure the integrity of the product.

Optional Features:

• Tecsonics® Bearing Wear Monitoring System.
• Special motor insulation for transformer cooling liquids other than transformer oil.
• Shaft rotation sight plugs to facilitate checking shaft rotation.
• Metric sized flange connections for international compatibility.
• Performance run-in testing and certified test curves.
• Various connectors are available to suit customer’s specific requirements.
• Motors available in single or dual voltage, single or three phase, 50 or 60 Hz frequencies.
• Large thrust face bearing.
• Custom designed transformer oil pumps that meet existing pump dimensions and performance requirements.
• Transformer Pumps suitable for rail car service.

Information on Transformer Oil Pump inspection, maintenance, repair and replacement

Design factors to consider when specifying a Transformer Oil Pump

Heavy Duty Transformer Oil Valves

Unifin’s Cardinal Pumps & Exchangers also manufactures a line of heavy-duty transformer oil valves ranging from 2″ to 8″ in size including ANSI standard and OEM specific flange configuration (such as the GE square shown to the right) bolt hole patterns. These valves are designed specifically for use on new transformers or as replacements on existing electrical transformers.

Field retrofit kits available for Westinghouse and McGraw Edison valves.

Design Parameters for Transformer Oil Cooling Click Here