Guarantees for temperature rise in electrical machinery, with special reference to large turbo-generators

In the past particularly, and to a large extent at the present time, it has been the custom for engineers to specify temperature rise guarantees of the order of 35° to 55°C. as measured by thermometer, the actual figure being determined by their individual experience, knowledge of the conditions under which the machine is to operate, and conservative ideas on the subject of desirable margins, and for manufacturers to supply apparatus to meet such guarantees.