Question

What is the formula of the diameter of the shaft?

(a) diameter of the shaft = 5.5 + (output in watt/rps)^1/3 mm

(b) diameter of the shaft = 5.5 – (output in watt/rps)^1/3 mm

(c) diameter of the shaft = 5.5 * (output in watt/rps)^1/3 mm

(d) diameter of the shaft = 5.5 / (output in watt/rps)^1/3 mm

This question was posed to me during an online exam.

This intriguing question originated from Design of Shaft topic in chapter Aspects of Design of Mechanical Parts of Design of Electrical Machines

Answer 1

Right option is (c) diameter of the shaft = 5.5 * (output in watt/rps)^1/3 mm

The explanation is: The output is first calculated from the operation of the machine. Next, the tachogenerator is used to calculate the speed of the machine and on the substitution of the values gives the diameter of the shaft.