Which is the Better Base Cooling Method?

Methods of Cooling of Transformer

The detailed description of cooling methods, one by one is given below.

Dry Type Transformer is cooled by the following two methods given below:

Air Natural (AN)

By Air Natural method the generated heat in the transformer is cooled by the circulation of natural air. When the temperature of the transformer becomes higher as compared to the temperature of the surrounding air, thus by the process of natural convection, heated air is replaced by the cool air. This method is also known as a self-cooled method. This method is used for cooling the smaller output transformer rating that is up to 1.5 MVA.

Air Forced (AF) or Air Blast

In this method, the heat generated is cooled by the forced air circulation method. With the help of fans and blowers, high velocity of air is forced on the core and the windings of the transformer. As the temperature inside the transformer goes beyond the standard safe level, an alarm is activated, and the fans and blowers are switched ON automatically. This method is used for transformer rating up to 15MVA.

Oil-immersed type transformer is cooled by the oil-air cooling method and oil-water cooling method.

Oil Natural Air Natural (ONAN)

Natural convection process is used for this type of cooling. The assembly of the core and windings are placed in the oil-immersed tank. As the core and the windings heat up the temperature of the oil in the transformer rises. As a result, the oil moves upward and flows from the upper portion of the transformer tank. This hot oil dissipates heat in the air by natural convection and conduction process, the oil gets cooled by the circulation of natural air and passes through the radiator again for the use of the transformer. This type of cooling is used for the transformer rating up to 30 MVA.

Oil Natural Air Natural Cooling of Transformer
Oil Natural Air Natural Cooling of Transformer

Oil Natural Air Forced (ONAF)

ONAF method is used for the cooling of the transformer of rating up to 60 Mega volts ampere. As discussed above that in ONAN method, the dissipation of heat is taking place by the convection process in which air is naturally circulated to cool down, but in this type, the forced air is used for the purpose of cooling the transformer.

The cooling of oil will be faster if the area of the tank of the transformer is increased finally, which result in the increase in heat dissipation level. As the fans and blowers are installed, a high velocity of air is forcefully applied to the radiator and cooling towers which will help in cooling oil more quickly and efficiently.

Its cost is higher as compared to another process where the circulation of oil and air is done naturally because a fan and blowers are attached as extra cooling equipment, in this method.

Oil Natural Air Forced Cooling of Transformer
Oil Natural Air Forced Cooling of Transformer

Oil Forced Air Forced (OFAF)

As the name itself says that both the oil and the air are applied by force for cooling of a transformer. The Heat Exchanger is installed through which hot oil is circulated with the help of a pump. Air is forced to pass on the heat exchanger with the help of high-speed fans.

This method is similar to ONAN, as when there is low load on the transformer the cooling is done by a simple ONAN method. However, as soon as the load is increased, the generated heat will also be more and therefore the sensor gives an alarm that the dissipation of heat has exceeded the safe value and as a result, the fans and pumps are switched on automatically. Thus, the cooling takes place by OFAF method.

Oil Forced Air Forced Cooling of Transformer
Oil Forced Air Forced Cooling of Transformer

Oil Natural Water Forced (ONWF)

In Oil Natural Water Force cooling method, the transformer core and the windings are immersed in the oil tank. A radiator is installed outside the tank, as the temperature rises and the oil heats up and moves upward, the heat is dissipated by the natural process of convection and oil is passed through the radiator, but the water is pumped and passed through the heat exchanger for cooling of the oil.

Oil Forced Water Forced (OFWF)

A heat exchanger is installed through which both oil and water are passed with the help of a pump. The level and pressure of the oil are always kept higher than that of water so that if any leakage occurs in the system the oil mixes with the water, but water does not get mixed up with the oil.

This type of method is suitable for large capacity of the transformer having rating as several hundred MVA or where banks of transformers are installed. Mainly this type of cooling is done for the transformer installed at the hydropower plant.

Oil Forced Water Forced Cooling of Transformer
Oil Forced Water Forced Cooling of Transformer


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41 related questions found

What are 3 signs of heat exhaustion being too hot?

Symptoms of heat cramps are painful contractions. Symptoms of heat exhaustion often include nausea, headache, fatigue and/or weakness, irritability, dizziness, confusion, thirst or signs of dehydration like a darkening of the urine.

What were the four heat related illnesses?

Heat-Related Illnesses (Heat Cramps, Heat Exhaustion, Heat Stroke) – Health Encyclopedia – University of Rochester Medical Center.

What are three safe methods for cooling food?

Approved methods to cool food

Ice-water bath and frequently stirring the food. … Ice paddles (plastic container filled with water and frozen) used to stir food in an ice-water bath. Adding ice as an ingredient (if water is an ingredient). Blast or tumble chiller.

Does dehumidifier help cool room?

Dehumidifiers can cool a room because it greatly reduces humidity which is the main cause of discomfort in a room. Humidity is that heavy muggy feeling you feel due to excess water vapor in the air. Dehumidifiers can air conditioners because all the air that is left will be dry and left to cool.

Can I use cooler in humid weather?

Window air coolers can be beneficial for humid locations, thus the southern part of India may require these types of coolers for better cooling. These coolers also have a provision of placing them on a trolley for easy mobility. Another type of air cooler that Indians can have is the Desert air cooler.

Why is faster air cooler?

The fast moving air increases the rate at which our bodies lose heat due to convection and evaporation. The faster moving air from the fan displaces the warmer air that is in direct contact with our skin. This enhances the rate of convective heat transfer, which means we feel cooler.

What are the three methods of cooling in air systems?

Types of Cooling Systems

Central Air Conditioners and Heat Pumps. Central air conditioners and heat pumps are designed to cool the entire house. … Room Air Conditioners. … Evaporative Coolers. … Ductless Mini-Split Air Conditioners. … State of the Art Cooling.

Which rapid cooling method is the fastest cooling method?

Forced (Fan) Cooling This is the fastest method of cooling, and it starts with the vacuum valves closing and the furnace backfilling with inert gas to a predetermined level (negative or positive).

How do you cool a hyperthermic patient?

Continuous application of cold water to the skin can be achieved by either sponging the patient or using a spray bottle. Placing a fan to blow directly on the patient while also spraying or sponging will increase the rate of evaporation, and thereby, will more rapidly decrease body temperature.

Which drugs can suppress the body's shivering?

Multiple 5-HT agonists and antagonists have shown efficacy on reducing shivering, including buspirone, tramadol, and ondansetron, among others. A single large dose of buspirone (60 mg) has a modest reduction in the shiver threshold by up to 0.7°C.

What is the safest way to carry an injured victim?

The safest anatomical position for an injured victim (from a transport perspective) is supine with his back straight, eyes forward, and arms and legs straight with his hands at his sides.

Is it OK to sleep in a room with a dehumidifier?

Yes it is perfectly safe to sleep in the same room as a dehumidifier. If you are particularly interested in a dehumidifier for the bedroom the noise level will be particularly important to you.

Is it cheaper to run AC or dehumidifier?

Generally, it is cheaper to run a dehumidifier than an AC if both units are of average capacity and have typical running times. … Portable dehumidifiers cost $25 to $350 per year overall, depending on their capacity. This breaks down to $2 to $29 per month, although this isn’t exactly a correct way of looking at it.

What should I set my dehumidifier at?

The optimal relative humidity level is between 30 and 50 percent, according to Energy Star (and 30 to 40 percent in colder areas during heating season). If the humidity is higher than that, it can breed dust mites, mildew, and mold, and trigger allergies.

What is the safest procedure for cooling food?

Cover pans of hot food and move them to a colder area e.g. a storage room, or stand them in cold water. You can also use ice to speed up chilling. This will make the contents of the pans chill more quickly. Stir food regularly while it is chilling down.

What is the 2 stage cooling method?

The two-stage cooling method is a Food and Drug Administration Food Code recommended procedure for cooling food in restaurants and foodservice establishments. In the two-stage cooling method, food must be cooled from 140 °F to 70 °F within two hours and to 41 °F or lower within four hours.

Why shouldn't you put hot food directly into a fridge?

Meher Rajput, Nutritionist at FITPASS explains, “Hot food should be brought down to room temperature-because if placed in the fridge(boiling hot) the salmonella bacteria can spoil the food very easily in the fridge.

Who is most at risk for heat related illness?

People at greatest risk for heat-related illness include infants and children up to 4 years old; people 65 years of age and older; people who are overweight or have existing medical conditions, such as diabetes and heart disease; people who are socially isolated; and the poor.

What are two heat illnesses?

Heat rash (also called prickly heat or miliaria), which is a stinging skin irritation that turns your skin red. Heat cramps, which are painful spasms in your muscles. Heat exhaustion, which is caused by too few fluids and long hours in high temperatures, causes heavy sweating, a fast and weak pulse and rapid breathing.

What causes extreme body heat? Hyperthyroidism occurs when your thyroid produces too much of the hormone thyroxine. Thyroxine affects the regulation of your body’s metabolism. An excess of this hormone can cause your body’s metabolism to increase, which leads to a rising body temperature. Graves’ disease is the most common cause of hyperthyroidism.