How Diesel Generators Work and Their Applications
The critical importance of electrical energy in our lives is undeniable. Unexpected power outages disrupt life in everything from the smallest households to the largest settlements. Energy losses can occur in electricity grids due to natural disasters, malfunctions, or human error. Therefore, preventing power outages in critical locations such as hospitals, military facilities, and data centers is ensured through generators. The word generator, derived from the English word “generator,” means an electrical power source.
Why do we use generators?
Diesel generators are used to provide backup power during power outages, to transmit power to areas unreachable by the power grid, and to meet sudden power needs. They are critical in areas requiring uninterrupted power, such as hospitals, factories, and data centers. Their portable design also makes them a preferred mobile power source in campsites, construction sites, and disaster areas. They offer a solution in agricultural lands and mountainous regions where grid infrastructure is absent.
How a Diesel Generator Works
Diesel generators consist of an internal combustion engine powered by diesel fuel and an alternator that converts this kinetic energy into electrical energy. Due to its self-ignition property, diesel fuel ignites under pressure in the combustion chamber. The energy released from combustion moves the pistons, and this kinetic energy is transmitted to the alternator to generate electricity. Diesel generators are produced in various power levels from 5 kVA to 4000 kVA, in single-phase or three-phase (1 or 3-phase) and parallel operation options. Sound-insulated cabinet options are available to reduce noise levels.
In short, before explaining the working principle of diesel generators, it is more helpful to understand how generators work in general. Diesel generators, one of the most commonly used types of generators, operate by combining internal combustion engines powered by diesel fuel with alternators that generate electricity. Diesel fuel belongs to the class of fossil fuels and, as in automobiles, reacts with oxygen to initiate the combustion process. This type of fuel has the property of self-ignition. The engine’s operating principle is based on compressing air to increase its temperature, and then injecting and burning diesel fuel at this high temperature. The energy released from combustion moves the pistons, and this mechanical energy is transferred to the alternator. The alternator then converts this kinetic energy into electrical energy to power the system.
Generator Power Concepts: Prime Power, Standby Power, and Continuous Power
Generator power ratings are classified as continuous power, prime power, and standby power. Continuous power defines the maximum power at which the generator can operate continuously under a constant load. Standby power refers to the capacity of the generator to support the load by switching on for short periods of operation. Prime power indicates the power level at which the generator can operate for extended periods under variable loads.
Main Components of a Diesel Generator
A diesel generator consists of an internal combustion engine, alternator, control panel, fuel tank, and chassis. The governor system regulates the engine speed, while voltage stability is ensured by the alternator voltage regulator. Synchronization control panels contain devices that monitor the generator’s operating parameters. The chassis supports the generator’s weight and reduces vibration with its anti-vibration properties. The cooling system ensures efficient engine operation, while the intercooler component cools the hot air in turbocharged engines.
The basic components of a generator set include a diesel engine, alternator, control panel, fuel tank, and chassis. Diesel engines are equipped with mechanical or electronic governors (speed regulators) that adjust the fuel quantity in generators. The governor system allows for precise adjustment of the engine speed. The alternator contains an electronic voltage regulator to provide voltage regulation. Control panels can be integrated into the generator chassis or be a standalone unit. These panels include: The generator’s speed, current, voltage, and pump systems are monitored using components such as relays, circuit breakers, current and voltage transformers, contactors, and drives. The chassis is designed to support the diesel generator set and is supported by anti-vibration mounts to reduce vibrations. Additionally, the chassis facilitates the transport of generators thanks to lifting lugs. Generally, in generator sets below 1600 kVA, the fuel tank is integrated into the chassis, while in larger capacity systems, these tanks are located as separate units. Each fuel tank has a level indicator. Cooling of the generators is provided by a radiator system, similar to that in automobiles. This system, along with an expansion tank and cooling fan, allows the generator components to operate at optimum temperatures. To improve diesel engine performance, a turbocharger and intercooler system may also be included. The intercooler cools the air compressed and heated by the turbo, increasing engine efficiency. Intercooler temperatures are continuously monitored on the control panel.
Basic Control Components of a Diesel Generator
Control devices used in generators are advanced systems that monitor and manage the performance of both the alternator and the diesel engine. These devices not only read current and voltage values but also monitor all generator parameters via analog and digital inputs/outputs. By sending signals to the voltage regulator and engine governor, they precisely control the generator’s frequency, voltage, and load conditions. Supporting various communication protocols, these systems act as the brain of the generator and have expandable capabilities with PLC programs when needed.
Diesel Generator Technical Specifications and Maintenance
Generator technical documentation specifies the brand, model, power ratings, physical dimensions, engine specifications (number of cylinders, displacement, fuel consumption), alternator details (number of phases, number of poles, insulation class), and control device specifications. Regular maintenance is essential for reliable and long-lasting operation of the generator. For malfunctions, support can be obtained from generator repair technicians or technical services.
What information is found in generator technical documentation?
Generator technical data sheets initially detail the manufacturer’s name, model, and power rating. Power ratings are generally given as standby power (ESP) and prime power (PRP), expressed in both kVA and kW. Whether the device is enclosed or not, and consequently its dimensions and total weight, are also included in this technical document.
The sheet then provides information on both the engine and alternator components. The engine section includes technical details such as brand, model, number of cylinders, engine displacement, and the presence of a turbocharger, while performance data such as fuel consumption, rotational speed, exhaust gas temperature, combustion air, and cooling air flow rates are also listed. This technical data is important for engine protection when programming the generator control panel.
For diesel engines, the fuel compression ratio is specified, while for gasoline engines, the air-fuel mixture ratio is indicated in the technical data sheet. The alternator section includes information such as the alternator’s brand, model, number of phases, number of poles (and consequently, operating frequency), power factor, insulation class, and protection class. The data sheet also indicates the model and type of the alternator’s compatible warning system, i.e., the automatic voltage regulator.
Applications and Types of Diesel Generators
Generators range in size from household generators (5 kW, 7.5 kW, 8 kW; normally the power unit should be specified in kVA, but in the market it is referred to as kW. In the literature, generators should always be referred to by their power unit in kVA) to large industrial power units, from 100 kVA to 3150 kVA. Different types exist, including gasoline generators, silent generators, mini generators, portable and mobile generators. Generator rental and portable generator options offer flexible usage advantages. The best generator brands can be chosen according to the needs and available space.