How to Analyze Engine Test Data?

We can judge the engine quality level by analyzing the following data

1. Torque and speed

Torque and speed are two key factors affecting the performance of generators. They are closely related to the output power, efficiency and operating stability of the generator.

Torque usually refers to the torque output by the engine and is an important indicator for evaluating the engine's ability to do work. It directly affects the generator's ability to convert electrical energy. Under the condition of a certain power, the greater the torque, the greater the power output of the generator at the same speed, which may increase the generator's output power. High torque means better acceleration performance at low speeds because it can more effectively transfer energy to the rotor of the generator and maintain stable power output.

The speed reflects the number of revolutions per minute of the engine. 50HZ normally maintains 3000 revolutions, and 60HZ normally maintains 3600 revolutions. The smaller the torque, the higher the speed. These two data together determine the power output curve of the engine.

During the analysis, it is necessary to check whether the torque and speed meet the design requirements, whether the changes under different loads are smooth, and whether the speed corresponding to the maximum torque and maximum power meet expectations. If the speed changes too much, the output power of the generator will be unstable. Unstable speed and torque require the motor to spend a lot of power to adjust the voltage, and the current generated is not of good quality.

2. Power

Power is the amount of work completed per unit time, which directly reflects the working efficiency of the engine. Check whether the power obtained by the test reaches the value marked on the nameplate, and the stability of the power output under different working conditions (full load, half load, etc.). The calculation formula is P = T × ω, where T is torque and ω is angular velocity (i.e. speed).

3. The relationship between torque, speed and power

Power (P) can be regarded as the speed of doing work. In a generator, when the speed (ω) remains constant, if the load increases, it means that the power (P) to be output must also increase accordingly. In order to increase the power output at a constant speed, the torque (T) must be increased.

Torque and load requirements: For a generator, torque reflects its ability to resist the load (that is, the resistance encountered when supplying power to the outside). An increase in load means that the generator needs to overcome greater resistance to maintain power output, so a greater torque is required to ensure a stable power supply.

Specifically, when the load increases and the generator attempts to slow down, the speed governor intervenes and increases the engine's output torque by increasing the fuel supply or other means to offset the deceleration effect caused by the increase in load and maintain the set speed. Therefore, it is through active adjustment to adapt to the needs of higher loads, rather than the load itself that directly increases the torque. The correct understanding should be that in order to cope with higher loads and keep the speed stable, the generator needs to generate greater torque.

Why not directly choose a generator with high power？

In fact, when designing and selecting a generator, the expected maximum load demand is indeed considered, and a device with sufficient power is selected accordingly. However, simply selecting a “more powerful” generator (meaning higher rated power and torque) may not always be the most economical or practical option. A higher powered generator may be larger, heavier, more expensive, and may be less efficient when operating under light or standard load conditions, wasting energy.

4. Fuel consumption and fuel consumption

The fuel consumption rate of a generator, also known as the fuel consumption rate, is an important indicator that reflects the economic performance of the generator. It indicates the amount of fuel consumed per kilowatt of power per unit time. This value is usually measured and calculated under laboratory conditions and is used as a relative standard to compare the operating efficiency of different generators.

The specific definition of fuel consumption rate can be the mass of fuel consumed per kilowatt-hour (kW·h) (usually in grams (g) or kilograms (kg)), or the volume of fuel consumed per kilowatt-hour (kW·h) (in liters (L)). For example, a common expression may be "220g/kW·h", which means that the generator will consume approximately 220 grams of fuel when it outputs 1 kilowatt of power and works continuously for 1 hour.

Fuel consumption is a key indicator to measure the economy of the engine. When analyzing, it is necessary to compare the actual measured fuel consumption with the industry standard to evaluate the fuel efficiency of the engine. The fuel consumption rate of generators on the market is basically 390. At the same time, observe the trend of fuel consumption changes with load to ensure that it operates within the high-efficiency range.

The fuel consumption rate directly affects the cost and efficiency of the generator operation. Generally speaking, the lower the fuel consumption rate, the better the economic performance of the generator, that is, it is more fuel-efficient at the same power output. When running at full load, the actual fuel consumption of the generator will be close to its rated fuel consumption rate; when the load is light, the fuel consumption per kilowatt-hour may increase relatively due to the reduced engine efficiency.

When the load of a gasoline generator is close to 80% of its rated power, it is generally considered to be the most economical operating state, and the fuel consumption rate is relatively low at this time. Because at this load level, the engine can efficiently convert fuel into electrical energy, neither too rich in oil nor too light to cause incomplete fuel combustion.

When the load of a gasoline generator is less than 20%, the fuel consumption rate will increase significantly. Under low load conditions, the engine combustion efficiency is reduced, and some fuel may not be fully burned, resulting in increased fuel consumption. In addition, long-term low-load operation may also cause damage to the engine, such as increased carbon deposits and poor lubrication.

As the load increases by more than 80% until full load, although the fuel consumption will increase with the increase in load, this is within the normal working range. Compared with low load, the engine operates more efficiently when fully loaded, although more fuel is consumed per unit time, but this is to meet the higher power output demand.

5. Cylinder head temperature and engine oil temperature

These two temperatures directly affect the reliability and life of the engine. Too high a cylinder head temperature may indicate incomplete combustion, cooling system problems or poor lubrication. The ideal cylinder head temperature should be 220 degrees. Too low a temperature will cause carbon deposits. Too high an oil temperature may cause the oil to deteriorate and reduce the lubrication effect. The ideal temperature range should be maintained at 105-120 degrees. If it exceeds the range, the cooling system and lubrication system need to be checked.