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4.3 Fluctuating speed at constant load
Two cases are considered: the speed varies in discrete steps over given parts of the duty cycle, calculate the equivalent constant speed from:

N = {(Na)a + (Nb)b + (Nc)c . . .}
where a, b, c are the proportions of the duty cycle with speeds Na, Nb, Nc respectively.

If the speed cycles continuously:

i) Plot for one complete cycle the value of N against time; from this plot estimate, Nav., the average speed.