Circle diagram constant air-gap induction motor images shown here, where, The circle diagram is drawn using the data obtained from no load and either short circuit or, in case of machines, blocked rotor tests by fitting a half-circle in points O and A. Beyond the error inherent in the constant air-gap assumption, the circle diagram introduces errors due to rotor reactance and rotor resistance variations caused by magnetic saturation and rotor frequency over the range from no-load to operating speed. Steinmetz equivalent circuit Circle diagram First conceived by A. Heyland in 1894 and B.A. Behrend in 1895, the circle diagram is the
Dividing a circle into areas solving the problem. By employing an inductive proof, one can arrive at a formula for "f"("n") in terms of "f"("n" − 1). In the figure you can see the dark lines connecting points 1 through 4 dividing the circle into 8 total regions (i.e., "f"(4) = 8). This figure illustrates the inductive step from "n" = 4 to "n" = 5 with the dashed lines. When the fifth point is added (i.e., when computing "f"(5) using "f"(4)), this results in four new lines (the dashed lines in the diagram) being added, numbered 1 through 4, one for each point that