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The load that a transformer carries without heat damage can be increased by using an adequate cooling system. This is due to the fact that a transformer's loading capacity is partly decided by its ability to dissipate heat. If the winding hot spot temperature reaches critical levels, the excess heat can cause

the transformer to fail prematurely by accelerating the aging process of the transformer's insulation.

A cooling system increases the load capacity of a transformer by improving its ability to dissipate the heat generated by electric current. In other words, good cooling systems allow a transformer to carry more of a load than it otherwise could without reaching critical hot spot temperatures.

One of the more common types of transformer cooling equipment is auxiliary fans. These can be used to keep the radiator tubes cool, thereby increasing the transformer's ratings. Fans should not be used constantly, but rather only when temperatures are such that extra cooling is needed. Automatic controls can be set up so that fans are turned on when the transformer's oil or winding temperature grows too high.

Maintenance of Cooling Systems

* Dry-Type Transformers:For dry-type transformers, the area in which the transformer is to be installed should have proper ventilation. This ventilation should be checked prior to installation to make sure it is adequate. Additionally, the transformer's radiator vents should be kept clear of obstructions

that could impede heat dissipation.

* Forced Air: If the transformer's temperature is being kept at acceptable levels by forced air from a fan, the fan's motors should be checked periodically to make sure they are properly lubricated and operate well. The thermostat that ensures the motors are activated within the preset temperature ranges should be tested as well.

* Water cooled systems: Systems that are cooled by water should be tested periodically to make sure they operate properly and do not leak. Leaks can be checked by raising the pressure within the cooling system, which can be done in various ways. If the cooling coils can be removed from the transformer, internal pressure can be applied by adding water. Otherwise, pressure checks can also be made using air or coolant oil, if the coils need to be checked within the transformer itself.

If the cooling coils are taken out of the transformer, the water cooling system as a whole can be tested. Here, the coils are filled up with water until the pressure reaches 80 to 100 psi, and left under that pressure for at least an hour. Any drop in pressure could be a sign of a leak. The other

equipment linked to a water-cooled system can be tested at the same time, such as the alarm system, water pump and pressure gauges. Also, the water source should be tested to make sure it has sufficient flow and pressure.

*Liquid coolants: When oil coolants are prepared they are dehydrated, and processed to be free of acids, alkalis, and sulfur. They should also have a low viscosity if they are to circulate easily. If a transformer is cooled by oil, the dielectric strength of the oil should always be tested before the

transformer is put into service.

Types of Cooling Systems

For oil immersed transformers, the options for cooling systems are as follows:

* Oil Immersed Natural Cooled (ONAN): Here, both the core and the windings are kept immersed in oil. The transformer is cooled by the natural circulation of this oil. Additional cooling can be provided by radiators, which increase the surface area over which a large transformer can dissipate heat.

Types of Cooling Systems

* Oil Immersed Natural Cooled

* Oil Immersed Air Blast

* Oil Immersed Water Cooled

* Forced Oil Air Blast Cooled

* Forced Oil Natural Air Cooled

* Forced Oil Water Cooled

* Forced Directed Oil and Forced Air Cooling

* Oil Immersed Air Blast (ONAF): In this case air is circulated and the transformer cooled with the help of fans. Fans allow one to have a smaller transformer for a given rating, since not as much surface area is needed for heat dissipation. This in turn can cut costs.

* Oil Immersed Water Cooled (ONWN): Here the transformer is cooled by an internal coil through which water flows. This method is feasible so long as there is a readily available source of a substantial amount of water, which is not always the case. This kind of cooling has become less common in recent years, abandoned in favor of Forced Oil Water Cooled (OFWF).

* Forced Oil Air Blast Cooled (OFAF): In this case, cooling is accomplished in two ways. Oil circulation is facilitated by a pump, and fans are added to the radiators to provide blasts of air.

* Forced Oil Natural Air Cooled (OFAN): For this type of cooling, a pump is included within the oil circuit to aid in oil circulation.

*Forced Oil Water Cooled (OFWF): Here, a pump within the oil circuit forces the oil to circulate out through a separate heat exchanger in which water flows.

The most dependable type of cooling system for a transformer is the oil-immersed naturally cooled (ONAN), which also produces the least noise. A forced-air cooled transformer (OFAF) is more efficient, but it is also noisier and less reliable on account of the possibility of fan malfunction.

The method of forced cooling has been used for many years now to increase the loading capacities of transformers. A transformer's thermal performance can be directly improved by the implementation of cooling systems. Consequently, it makes sense to avoid excess heating and accelerated aging within a transformer by using the appropriate cooling system.

To know more about transformer cooling systems and distribution transformers visit Pacific Crest Transformers. website

Evaporative Water Cooler - This Water Cooled Condensing Unit Is No Swamp Cooler

This unique cooling technology from Freus, shouldn't be confused with a swamp cooler. Although water is used to assist with the cooling, it is sprayed over condensing coils rather than pads.

The water cooled condensing unit is a residential application of the 250 ton split system chillers already used by commercial buildings. Think of this technology as a mini-chiller for residential use.

Evaporative water cooler units for split system air conditioners have a number of advantages over air-cooled units. Water removes heat from the condenser coils far more efficiently than air. This reduces the temperature of the compressed R-22 refrigerant, which in turn reduces the work load of the scroll compressor. Not only will the compressor last much longer, there is only a minimal loss of cooling efficiency when the outdoor temperature exceeds 100 degrees.

Typical air cooled units can lose as much as 25% of their efficiency at the same temperature.

How much can you save with a water cooled condensing unit?

Charles Mullin, a casino worker who lives in North Las Vegas is also single. So every utility bill comes from his lone paycheck. That's why he switched the air conditioning system on his 1,500-square-foot home to a water cooled condensing unit.

"Before I installed it, I had my thermostat set at 75 to 78 degrees to try to keep my electric bills down," he said. "I tested the new system at 65 degrees – felt like a meat locker. My bill went down to $86. That's about a 45-percent savings and the house was set cooler."

Mullin told all his friends about the units and the savings he's seen. He figured the Freus system will pay for itself in about two years.

Richard Waite, president of Hal Mechanical, installer of Mr. Mullin's water cooled AC, said they are specifically made for the desert climate.

"The only extra that's needed to swap out an old air conditioning unit for a new water-cooled one is to run a water line to it. The unit has an automated system, similar to a toilet tank, keeping the water at the correct capacity. The system also flushes itself to avoid calcium buildup."

Due to the almost constant capacity, the condenser size does not need to vary due to climate zones, like air-cooled units. The Freus is installed in much the same manner as an air-cooled condenser and has the unique ability to service multiple air handlers. This provides the space saving convenience of housing two or three compressors (up to 10 total tons) in a single cabinet.

Jim Kilby of Green Valley, a casino management professor, replaced his 10-year-old air conditioning units, one 5-ton and one 3-ton, with two water-cooled ones of roughly the same capacity. He figures his electric bills dropped by a third.

"The hotels have been using this technology for years," Kilby said. "When you think about it, water does a better job of cooling the air than air. It just makes sense."

Whether you call them evaporative water coolers or water cooled condensing units, this mini version of the 250 ton chiller is sure to revolutionize desert cooling.

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http://www.alternative-heating-info.com offers a unique look into geothermal heating and cooling, outdoor furnaces, corn boilers, radiant heat, solar heating systems, and pellet burning stoves.

What is the advantage of an air cooled outboard motor?

I bought a Sears Ted Williams 7.5 HP that says "air cooled" But it also says to run it in fresh water after running it in salt water. So, what's the advantage?

I dont think air cooled is an advantage over liquid cooled. In the marine environment the worst thing that can happen to your engine is salt water. With liquid cooled outboards the salt is sent through the the block, but it runs cooler, which helps the engine live longer. This a liquid cooled engine you have to run it fresh water to flush as much salt as possible out of the block. The air cooled engine you have to run in fresh water because salt still gets on the lower unit and in the exhaust if its low enough. The air cooled engine doesn't run salt through the block but it runs warmer, I think that's a trade off.

Traditional Qatari buildings save on air-conditioning
Doha: Buildings and places need to be designed and developed in a sustainable way to allow communities to be less reliant on air conditioning and cars. Sustainable design can lead to cost and energy efficiencies, enhanced lifestyles and a reduced impact on climate change.

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