Discussion on “a method of determining the correctness of polyphase wattmeter connections” (Kouwenhoven), New York, Feb. 9, 1916. (see proceedings for February 1916)

W. H. Pratt: The author has made a very large amount of painstaking effort in collecting and analyzing the behavior of the meters with these miscellaneous connections. There is one point that is emphasized throughout the paper, that this checking must be made under balanced load conditions except in one particular case. There should be a great deal of care exercised in deciding whether you have a balanced condition in applying the check. The fact that you use a motor which tends to take a balanced load does not necessarily mean that the load will be balanced unless the voltages are strictly balanced. A very small unbalancing of voltage may mean a very large amount of unbalancing in the power station. This point emphasizes the fact that you should always be very particular in following the diagrams of connections. It is a very easy matter to systematically arrange most work so that you can follow the diagrams just as if you had a column of figures to add, and then very carefully do the work. There is a temptation, however, to rely on the check, but a check should be made bearing in mind that you have limitations which might seriously affect the conclusions.