Since, and unless electricity has properties I’m not aware of, it’s not possible for electric power plants to produce only and EXACTLY the amount of electricity being drawn at an given time, and not having enough electricity for everyone is a VERY bad thing, I’m assuming the power plants produce enough electricity to meet a predicted average need plus a little extra margin. So, if this understanding is correct, where does that little extra margin go? And what kind of margin are we talking about?
In: Engineering
The standard in NA is to supply 120V AC to homes within +/- 10% (132V to 108V). Depending on the current draw of the system that voltage will drop or increase because of Ohm’s law (Power=Voltage x Current). The utilities aim for a power level that will provide enough current based on historical averages at 120Volts and if that level is not required the voltage goes up and sucks up the extra power. If it exceeds the average like during a heat wave when all the air conditioners are turned on, then the total current draw exceeds the available power and you see the voltage drop to below the 108VAC level and that causes a brown out.
For industries that require very stable power input or are prone to having spikes in their power consumption for their machinery they have banks of large capacitors installed to suck up additional power for reserve that can be used in the event of major swings in the power grid. Google the power triangle if you want to know about reactive power vs real power. The utilities also have massive banks of capacitors to help stabilize power draw.
So basically, any excess power is factored into the system by having a standard that allows for a range of power to be delivered to a household. Its up to the appliance manufacturer to cope with that range of power.
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