Knowledge of diesel generators

Diesel generator refers to a generator driven by a diesel engine, which is composed of an internal combustion engine and a generator fueled by diesel.

Among them, when the diesel engine is working, it sucks in the air in the cylinder of the diesel engine, and is compressed to a high degree due to the movement of the piston, reaching a high temperature of 500~700 °C. The fuel is then sprayed into the high-temperature air in the form of a mist, and mixed with the high-temperature air to form a combustible mixture, which automatically ignites and burns. The energy released during combustion acts on the top surface of the piston, pushing the piston and converting it into rotating mechanical work through the connecting rod and crankshaft.

The generator is a device that converts the mechanical work provided by the diesel engine into electrical energy, and the working principle is based on the laws of electromagnetic induction and electromagnetic force. Therefore, the general principle of its construction is to use appropriate magnetic and conductive materials to form magnetic circuits and circuits that carry out electromagnetic induction with each other, so as to generate electromagnetic power and achieve the purpose of energy conversion.

Due to the large capacity, fast starting, easy operation, parallel operation and long continuous power supply time, it can also operate independently, does not run in parallel with the regional power grid, is not affected by power grid failure, and has high reliability, so it has a wide range of applications in most schools, enterprises, governments and even families in China. However, due to the high cost of power generation, diesel generator sets are mainly used as emergency backup power supply, or in mobile power stations and some areas where large power grids have not yet arrived.

The speed of diesel generators is usually below 1000 rpm, and the capacity is between several kilowatts and several thousand kilowatts, especially for units below 200 kilowatts. It is relatively simple to manufacture. The torque output on the shaft of the diesel engine fluctuates periodically, so the generator works under severe vibration conditions. Therefore, the structural components of diesel generators, especially the rotating shafts, should have sufficient strength and rigidity to prevent these components from breaking due to vibration. In addition, in order to prevent the uneven angular velocity of the generator due to torque ripple, resulting in voltage fluctuations and flickering lights, the rotor of the diesel generator is also required to have a large moment of inertia, and the natural torsional vibration frequency of the shaft system should be more than 20% different from the frequency of any alternating component in the torque ripple of the diesel engine, so as to avoid resonance and cause shaft breaking accidents.