What do the API motor/generator features cost and what do they buy you?

The API 541, 546 and 547 large motor and generator standards require many features that are not found in “regular” large electric machines. These features lead to a more reliable machine, but they also add to the first cost of the machine. This paper compares the costs and benefits of some of the more significant features that may be specified and makes recommendations as to which optional features should be purchased for particular situations.