The retardation method of loss determination as applied to the large Niagara Falls generators

Institute literature is apparently lacking in information regarding retardation tests. The purpose of this paper is to point out certain advantages of the method and to describe the procedure followed in testing the Niagara generators. The basis of the method is first given with the fundamental formula upon which it depends. Since it requires the use of the moment of inertia, or “fly-wheel effect” W. R
²
, methods of determining this value are given, and it is pointed out that it can be determined by test. The methods of determining the speed of rotation and its rate of change are given, with a description of the devices used for automatically recording the necessary data and the method of interpreting such data. It is shown how the determination of losses over a range of speeds increases the accuracy of the determinations. General methods of testing are described, with a connection diagram and an outline of the necessary precautions. The detail procedure for tests for different losses is given. It is shown how this method of test furnishes data for the separation of the friction from the windage. The division of mechanical losses between generator and turbine in a specific case is also described. The procedure in determining the electrical losses from the test data is given and some observations made regarding the apparent desirability of the further refinement of the method.