The physical efficiency, performance, or condition of a machine is found by comparing actual parameters against an ideal model. Deterioration is typically the cause of difference in the readings. Methods include High Voltage Discharge analysis on motors, flow performance testing on pumps and compressors. Condition monitoring by a simple head-flow test near duty point using repeatable measurements is common practice for pump performance testing but these results can be expanded further. An extension of this method can be used to calculate the best time to overhaul a pump based on balancing the cost of overhaul against the increasing energy consumption that occurs as a pump wears.