You live on an island with your sick husband. There are a few fishermen on the island but everything is barely on the civilized side of things.
The electrical powersystem that you rely on is based on a motor-generator. You have a fuel pump that is feeding a motor that drives a generator that produces electricity. This electricity runs the iron lung that your husband is strapped into as well as other medical equipment that is keeping him alive. There is plenty of fuel, enough to last for many years.
This works nicely for a year or two, but then in the autumn someone send you an electric heater. This is nice as you are not so keen on choping wood in the rain. But after you have installed it, it gobles up a large amount of electricity and your generator is now taxed beyond capacity. This means that your electric heater only gets 80 percent of what it could use to generate heat with. So your room is at 19 C instead of 21. You medical equipment is also a bit starved for energy but still functional. And your husband might suffer a bit because of it, but he is not in danger of dying.
The real problem however is the fuel pump. While it had enough power it would feed the generator all the fuel it could burn. But with a overburdened power system it now only feeds 80% of the fuel compared with earlier. And this actually affects the generators ability to produce power. Gradually the generator is affected by a compromised and limited fuel supply. The motor slowly reduces its output of power and the electric generator no longer produces as much electrical power.
First it is just a slight incremental change, but as this affects the fuel pumps as well as the rest of the system, it gets worse and worse. You worry as it gets colder and colder. And your worry grows into panic as half the medical equipment is flickering because of the inadequate power and the other half is beeping loudly while red diodes are blinking vigorously. Your husband is turning a bit blue in his face.
As you look around in desperation, your eyes catches the cord for the electric heater. You swiftly unplug the heater and try to listen for any change in the note of the generators hum. First you cant hear any difference, but then you notice that some of the blinking diodes stopped blinking. And slowly slowly the system picks up. It gets colder and colder, but the energy system is improving by the minute and you start to breathe again. As you light a fire in the old iron stove you try to understand how this could happen.
The real problem however is the fuel pump. While it had enough power it would feed the generator all the fuel it could burn. But with a overburdened power system it now only feeds 80% of the fuel compared with earlier.