Class B-Installations from 10 to 50 horse-power, irrespective of number of motors, 65 per cent of the connected load. Class C-Installations all over 50 horse-power, irrespective of the number of motors, 55 per cent of the connected load. These figures represent the average figures of our directcurrent system, and at the present time we are working under, that schedule on our alternating-current system. MR. SANDS: I understand that in England demand indicators that will not register a maximum demand of less than 15 minutes, or a half-hour, or an hour, are being used for motor work. I ask what you think is the fair time limit on demand indicator for power work. MR. FERGUSON: That would depend on the size of the power station. In a large station, like that of New York, or Philadelphia, or Boston, or Chicago, it would not make so much difference; an hour could be used without any difficulty. If you were in a small town, where the size of the power-house was small, you would have to make the limit of time less, because otherwise you would tax your generators if you had great, high flashes, lasting for five or ten minutes. In a large system these peaks do not come together and overlap-that is, are not coincident-so you would not be bothered even if you used a longer time between readings. MR. SANDS: Don't you think a man with a steam plant can overload his plant, for a period of 10 or 15 minutes, thirtythree and one-third per cent, with no appreciable difference to him in the cost of power? We must meet that, in a measure, in fixing our demand. MR. GEISER: As I understand Mr. Ferguson's position, the method would be applied to inductive load only; that is, only to furnishing power service for separate motor installations, independent of the lamp load. All of our load is not inductive, and the same method would not apply to non-inductive load that applies to inductive load. In many places the power service is separate from the lighting service, but every day the demand is becoming greater for all kinds of service from one service connection, through one meter. In our own place we have it entirely that way; only one meter for all kinds of service, inductive and noninductive. There are various devices that may be attached to the service, either large or small, and we can not tell to-day what is going to come on to-morrow and whether it is going to be inductive or non-inductive. We ought to have meters that will measure that demand in such a way that we can take care of all the customers, all kinds of loads, so far as possible on one set of meters with one set of charges. I do not know how the question affects most of the members here, but with us we find the maximum demand meter does not entirely satisfy the customer; he would rather contract for a definite demand. Consumers want to know beforehand on what basis their maximum demand is put and on what basis they are being charged. Something in the nature of a current-limiter, it seems to me, would be an improvement over the maximum-demand meter. There is a demand for an instrument that will limit the demand in such a way that the customer will know it, at least if he exceeds that demand. MR. HARTMAN: The proposition advanced by one of the recent speakers, that the peaks integrated over a half-hour or an hour should be taken as a fair average, seems too high. Take, for example, an elevator load; we all know that if we were to take as its maximum the average over a period of an hour or a half-hour we should be allowing entirely too little. The Niagara Falls, Lockport and Ontario Power Company has recently installed a very large transmission system, and has adopted as an average the one-minute peaks over the month; the thirty highest one-minute peaks are taken as representing on the average the demand for which it must charge in order to get a sufficient amount for its fixed charges. MR. DION: I would ask Mr. Ferguson, assuming that the Wright demand meters are used to determine the maximum load on motors, large and small-such as we find in a large city, alternating-current motors-whether the lag of the Wright demand meter furnished in this country is such that the starting current of the motors will not be recorded. MR. HALE: We have Wright demand meters on practically all of our direct-current power business, and we find no trouble at all from the starting current. MR. FERGUSON: I will answer the question of Mr. Dion regarding the operation of the Wright meter. It rises to about 80 per cent of the true maximum in five minutes, then it continues very slowly until after the load has been on, say, for 20 minutes, when it reaches the true maximum. The Wright meter does not take into consideration flashes or momentary peaks. If you keep shoving on peaks, one after another, it will force the reading of the instrument up more nearly to the true maximum. We do not apply the Wright meter to our alternating-current service; we use a system of percentages, which I explained, that were arrived at through a study of the ratio between maximum load and connected load in our direct-current business; assuming that what was fair for the direct-current was fair for the alternating-current business. I think the simplest way to get at the whole subject would be to appoint a committee to look further into the matter. The Association of Edison Illuminating Companies has a committee on meters, and that committee is considering this subject. It is working with the manufacturers on a meter that can be used for general purposes. I move, Mr. Président, that a committee on meters be appointed by the president to investigate the whole subject of meters, with especial reference to the particular subject we have been discussing this morning. (The motion was carried.) THE PRESIDENT: We will now have the report of the committee on standard rules for electrical construction and operation, of which Mr. Ernest H. Davis is chairman. We owe great debt to our preceding presidents for the manner in which they have conducted our relations with the insurance interests, and I am glad to have a man who has been foremost in this matter to read this report. Mr. Davis read the following report: REPORT OF COMMITTEE ON STANDARD RULES FOR ELECTRICAL CONSTRUCTION AND OPERATION To the Members of the National Electric Light Association: Your Committee on Standard Rules for Electrical Construction and Operation has had but little to do during the past year. No complaints of members as to acts of inspectors, or others interested in fire underwriting, have been received; and your committee therefore assumes and believes that the relations between the two interests are on a more harmonious footing, which it is hoped and expected will continue and improve. Rule 13-A of the National Electrical Code, relating to the grounding of low-potential circuits, has been seriously objected to as being impractical and oppressive, and the attention of the Fire Underwriters was called to the objection made. Mr. C. M. Goddard, on behalf of the Underwriters' National Electric Association, on February 1, 1907, wrote to the secretary of this association about the objections made to Rule 13-A, and stated that it had been decided to call the attention of the following parties to such objections: National Conference on Standard Electrical Code The Association of Edison Illuminating Companies International Association of Municipal Engineers and various manufacturing companies. No action on the proposed changes in said Rule 13-A was taken at the meeting of the Electrical Committee of the Underwriters' National Electrical Association held in New York on March 27 and 28, but it was arranged to have this matter referred to a committee, which before it reported should confer with committees from the National Electric Light Association, the American Institute of Electrical Engineers, the Association of Edison Illuminating Companies and the International Association of Municipal Engineers. The report of the committee on the grounding of alternating-current secondary circuits, as also of Mr. W. H. Blood, Jr., the insurance expert of the association, will no doubt contain fuller details as to what has been done. The association, through a proper committee, should carefully consider the provisions of Rule 13-A, as it now stands, and suggest changes to adequately protect central-station interests. Respectfully submitted, ERNEST H. DAVIS, Chairman, (On motion, the report was received.) For the Committee. THE PRESIDENT: I will announce as the committee on meters the following gentlemen; Louis A. Ferguson, of Chicago; Alex Dow, of Detroit, and J. E. Montague, of Niagara Falls, with power to add to their number. We will now take up the programme under the head of Commercial or New-Business Day. Mr. W. W. Freeman will take the chair. (The report of the Commercial Programme will be found in Volume II of the Proceedings.) |