An electrical power plant is responsible for providing continuous electric supply without an interruption. A good power system should be able to fulfill the maximum demand of the connected load.
Spinning, cold, and hot reserve capacities represent the generating capacities of stations.
Cold reserve
The generating capacity of a reserve which is available for service but is not operational.
Hot reserve
The generating capacity which is in operation but not in service.
Spinning reserve
The generating capacity which is connected to the bus and is ready to take the load.