if you have a generator and are having problems with it when you connect it to the items you are trying to power, this article might help you. It applies to all generators, petrol and diesel, small and large. In most cases the issues will be the same.
On larger generators, there may be protection for overload. Overload happens when the generator is not big enough for the items you are trying to connect to it. For example, if you have a 10kW generator and try and connect 11kW, it will be in overload.
If the generator has protection for overload, then the unit will likely shut down and display a warning on the control panel. but what if it doesn't? What are the symptoms and how can I tell the unit might be over loaded.
The first clue is the engine noise - when you connect items to the generator, you will here the sound change - this sound is the speed changing as the generator slows down absorbing the impact of the load you have applied to it. Normally this will last a second or two and the geenrator will return to the previous running state.
In cases where the load is too large the speed will not return, or the generators engine will stall and shutdown entirely. The power a generator can provide is limited by the amount of fuel and air that can be injected into the cylinders for combustion. A 10kW generator will be set to allow enough fuel to produce 10kW (plus a little bit to allow for governing usually.) If you try and apply 11kW, because there isnt enough fuel, the speed will start to drop or the engine could stall. If you experience this you have probably tried to overload your generator.
When else could cause this? A fuel restriction or air restriction would also cause this problem, try changing your fuel filter and your air filter to see if this helps. You could also have poor quality fuel - if your fuel is old or has been contaminated it won't be providing the same amount of power per litre, so you will end up with an underpowered generator.
There are of course many reasons that a diesel generator can shut down, so this is just one answer to why it might be happening. If the generator only shuts down when you apply the load and connect it to the devices you want to power, then overload is a strong possibility.