Patent ID: 8374731

Claim:
A cabinet for storing electrical components and a cooling system for cooling the electrical components, such cooling system comprising: a sensor disposed to sense the temperature of the cooling air drawn into the cabinet; a pair of electrical chassis, each one of the chassis having: electrical component; at least three fan units, each one of the fan units having a fan for drawing external cooling air into the cabinet in response to a desired fan speed signal fed to the fan unit and for producing an actual fan speed signal representative of the actual fan speed; a fan control unit, responsive to the sensed temperature and the actual fan speed signals produced by the at least three fan units for producing the desired fan speed signal for each one of the at least three fan units, such fan control unit producing signals to: (a) generate the desired fan speed signal for only a selected two of the at least three fan units to operate only said selected two of the at least three fan units, one of the at least three fan units being unselected and being inhibited from operation while monitoring operation of said selected two of the at least three fan units for a failure in one of the selected two of the at least three fan units; (b) upon detection of a failure in one of said selected two of the at least three fan units, the fan control unit signals inhibit operation of the failed one of the selected two of the at least three fan units and producing the desired fan speed signal for the unselected one of the at least three fan units to place in operation the unselected one of the at least three fan units; and (c) upon detection of a failure in at least two of the fan units in such one of the pair of chassis, the fan control unit signals removes power from the electrical component to shut such component down while stand-by power remains to power the fan control unit.