Function Cost of Low-power, Three-phase Squirrel-cage Induction Motors

This short paper looks at the function costing of low-power, three-phase squirrel-cage induction motors. Function costing is the estimation of the costs of engineering systems from the quantified functions performed by their elements. For the motors considered, the cost is largely proportional to the full-load output torque, with only a small variation attributable to the pole number. However, two-pole motors are an exception; they cost up to 70% more per unit torque. An explanation of this result is proposed. At the date of the prices used ( February 1992), the approximate price of the sampled motors with four or more poles is£ 61 + £ 5.30 per newton metre of output torque, and that of the two-pole motors is £ 49 + £ 9.60 per newton metre.