Question

Which are the important criteria related to the power ratings of the machine?

(a) Heat should be prevented from generation

(b) Heat should be dissipated through power ventilation, irrespective of the time

(c) Heat should be prevented through power ventilation within a short time period

(d) Heat should be converted to some useful form

I got this question in a national level competition.

Enquiry is from Rating of Machines topic in section Thermal Design Aspects of Electrical Machines & D.C of Design of Electrical Machines

Answer 1

Right answer is (c) Heat should be prevented through power ventilation within a short time period

For explanation: Due to the components present in the machine, I^2R losses occur in the machine. Due to this, heat is produced, and proper thermal ventilation should be provided to prevent the machine from breakdown.