Generators come in a variety of sizes. We used smaller generators in our homes or apartments to large generators in large companies, malls, and even offshore oil drilling sites. Generators of either size have one thing in common: they all generate heat. When we turn on generators, they produce heat, which we can attribute to coils inside. To avoid damage and assure continuing service, we must cool down our electric generator and maintain it at all times. Most generators have many conductors, each of which creates heat when current flows through them. Heat may quickly accumulate inside the gadget and must be evacuated with care to avoid harm. The heat may be excruciating.
We can experience damages in our windings when we can't adequately treat the heat. A variety of problems can arise, including clearance and balance issues. However, using different cooling systems, we can reduce the heating to a safe level. When we have excessive temperature rise in our generator, our winding insulation breakdown and causes it to shorten. It is possible to reduce the possibility of generator damage by cooling the generator regularly. In the end, this saves time and money by that stress and avoiding the need for maintenance. Besides, heating in our generator attributes to power loss and lowers down its efficiency. Heating attributes about 10% of the power losses in our generator.
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Heat and Heat Transfer
Heat is a consequence of energy transformation. For example, a steam turbine runs by applying pressurized steam, which will cause a rotation to it. Then, the turbine drives an electrical generator to enable us to have usable electricity. As a result, we produce electricity through energy transformation and heat at the same time. The cause of heating is the friction between bearings and from the coils or winding. It shows that heat is an inevitable event in the energy transformation process. We could not eliminate it, but we can regulate it at a safe level for operation.
If we can effectively reduce the heat in our electrical generator, we can prevent the rapid deterioration of the windings happens. We can avoid critical concerns in energy generation. However, we can cool down the heat in our electrical generator by either pumping out the heat or allowing fluid to pass through the generator to cool it down. We can substantially decrease the issues that we can encounter due to excessive heat by regulating it. It allows us to have fewer repairs. Before all of that, the fundamental premise of generator cooling is heat transfer.
In heat transfer, we consider the temperature and flow of heat in the system. Temperature is the amount of thermal energy, while the flow of heat is the movement of thermal energy from a system with a higher temperature to a lower temperature. We apply the concept of heat transfer to cool down our electrical generator. In simple words, we inject a cooling agent into the system, and due to heat transfer, we can have the temperature regulated at a safe operating condition.
Heat transfer by convection is a typical approach in generator cooling. Convection occurs when we heated fluid and then travel away from the source, which carries the thermal energy along. The fluid above a hot surface expands, becomes less dense, and rises. In generator cooling, we allow the fluid to pass through the generator windings, and as it flows through the winding, it carries out the heat in the winding, which results in the generator cooling down.
The fundamental cooling concepts. We forced air movement in a closed circuit (to limit dirt entry) by a fan on the rotor shaft. It results in cooling air pass through ventilation ducts in the stator center, between rotor poles, and through the air gap (a few millimeters) between the stator and rotor. For generators with a high power level, we used water cooling. We used temperature sensors to monitor the temperature of the stator windings, bearings, and the generator's cooling air/water. We set a temperature alarm, either single or clustered, are activated at the primary watchkeeping point.
When we used an air cooling system, we circulate air through the windings to bring the temperature down. The engine fans collect cool air from the surrounding environment and distribute it over the generating set in an air-cooling system. It keeps the generator from overheating. We usually integrate air-cooling in portable generator sets and backup generators up to 22 kilowatts.
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The air-cooling system is either open-ventilated or entirely enclosed. The open-vent system takes outside air and exhausts it back into the atmosphere. It allows for the air to be released right back into the atmosphere. It pulls in the air and pushes it back out into the surrounding area. For the enclosed systems, we circulate the air within a sealed unit. We keep the air in place and recirculate the air. As it does, we keep the generator cool.
For a liquid-cooled system, the generator uses oil or coolant to maintain the temperature of the internal parts down in a liquid-cooled system. We used a radiator and a water pump for cooling. The pump distributes the cooling liquid to the generator winding. We transferred the heat from the generator to the coolant, which cools as it flows through the radiator. A generator with more than 22 kilowatts uses liquid cooling. Liquid-cooling systems are costlier to manufacture than air-cooled alternatives, but they are more durable and robust.
The following are the differences between a liquid-cooled system and an air-cooled system: For starters, air-cooled systems are simply ineffective for larger systems, typically those with more than 22 kilowatts, whereas liquid-cooled systems are the most prevalent alternative for commercial and industrial environments. Second, liquid-cooled systems are more complex and have more components, whereas air-cooled systems are less efficient with larger generators. However, they are generally a more economical solution for individuals searching for a simple system for a smaller generator. Third, air-cooled systems are less complicated to maintain than liquid-cooled ones. We have low-power electric heaters inside the generator to prevent condensation on the winding insulation when the generator is on standby or maintenance.
To summarize, generators produce heat, which we need to regulate so that winding insulation will not deteriorate. Internal heating in the windings and magnetic cores of both rotors and stators can cause power loss. Generator cooling is crucial because damage to the windings occurs quickly. Air-cooled and liquid-cooled systems are the most commonly used cooling agents. When it's air-cooled, it's either open-ventilated or completely sealed. Water-cooled systems are sometimes known as liquid-cooled systems. The two cooling processes differ in terms of efficiency, cost comparison, maintenance, and noise level.
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