Short-term reserve of electricity generating capacity
An idealized representation of the four kinds of reserve power and the time intervals after an unexpected failure that they are in use.[1]
In electricity networks, the operating reserve is the generating capacity available to the system operator within a short interval of time to meet demand in case a generator goes down or there is another disruption to the supply. Most power systems are designed so that, under normal conditions, the operating reserve is always at least the capacity of the largest supplier plus a fraction of the peak load.[2]