The generator is driven by the diesel engine. When the electrical appliance is connected, the internal coil of the generator and the external electrical appliance form a circuit, which will generate current. When there is current, the electromagnetic force resistance torque will be generated. The energy is conserved. How much electrical energy is used to resist the torque? How much extra work needs to be done. For a generator with a stable speed, the electromagnetic resistance does more work, which means that the resistance torque is large. In layman's terms, the greater the power of the electrical appliance, the heavier and harder it is to rotate. When there is no electrical appliance, there is no current inside the generator coil, and the coil generates electromagnetic resistance torque, but the bearing and belt of the generator will have resistance torque, which also consumes the power of the diesel engine. In addition, the diesel engine itself is a four-stroke, and only one of them Doing the power stroke and maintaining its idling speed also requires fuel consumption. The efficiency of the diesel engine as an internal combustion engine heat engine is also limited.

When the power of the generator is large and the power of the consumer is small, these power losses may be larger than the power of the consumer. Diesel engine power is difficult to make small, so the minimum power of diesel generator is several kilowatts. For electric tools of several hundred watts, this load can be ignored. The above confirms what you said about the same fuel consumption with or without electrical appliances.