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ing of the American Institute of Electrical Engineers, New Yorh, January 17, 1893-1 VicePresident Lockwood in the Chair.
ELECTRICAL RECORDING METERS.
BY CARYL D. HASKINS.
It was my first intention to present this
Electrical Recording Meters” or “ Electricity Meters” in the form of a strictly technical monograph, dealing with each of the more prominent theories of meter construction separately and fully. Upon outlining this plan, it at once became evident that to do so I should be obliged to devote some four or five hundred pages of closely written manuscript to my subject matter, and should have been obliged to deliver the final three quarters of my paper during the early morning hours succeeding the session. I therefore changed my plan, and now propose to briefly describe and discuss the leading elements which, singly or combined, have gone to make up the typical meters which have been presented to the public up to the present time. I find myself limited to generalities, and strictly technical considerations bave necessarily been neglected that the field might be approximately covered.
A brief history of the evolution of the electric meter would be very appropriate, but repetition is odious, and I beg to refer all who are interested in the early history and genealogy of the meter to that most interesting and complete paper on this subject read before the Institute? by Mr. George W. Walker, May 21st, 1891.
The earliest meter patent was granted in 1872 to Mr. S. Gardiner, Jr., of New York City, and the principle of a magnetic or electro-magnetic release for a simple clock movement, is preserved in two or three so-called time-counters to-day, and is doubtless very useful for many purposes ; as for example in the Spaulding clock for registering the hours of use of a motor, or in other similar devices for registering the hours of use of arc circuits. These devices I shall neglect; they are not meters within the true sense of the word, and their simplicity is obvious.
1. Transactions, vol. viii., p. 351.
Before undertaking any description, a few words may be appropriately devoted to the question of the unit by which it is inost desirable to measure electrical power in use.
The ampere has been, perhaps is to-day, the popular unit for the measurement of electricity supplied ; yet, on careful consideration, how very meaningless for work of this kind, is the ampere unit. It would only find a parallel in the very ingenious early settler of Maryland, who bought six linear miles of land from the trusting Indians.
Had we but one standard voltage in use for lighting and for power, and for other purposes, no unit could be better than the ampere-bour for meter measurement; but unfortunately or fortunately, as the case may be, there is scarcely a potential, between 5 and 2,000 volts, which does not more or less imperatively call for measurement by meter to day, and if the ampere unit is to be retained, then it will become necessary to reconcile ourselves to the use of an endless number of constants, or to a still more endless schedule of ampere-hour rates.
We wish to measure power delivered; in fact we wish to know how much coal a group of lamps is consuming. This points directly to the watt, and I venture to assert that careful consideration will invariably show that the watt is the only true unit for the measurement of electricity by meter. Unless, perchance, we adopt the cubic foot, as has at least one central station in the United States; a very amusing but equally practical demonstration of American ingenuity.
The earliest successful meters if we consider classes rather than individual instruments, were the chemical meters, closely followed by thermo-meters.
The chemical meter is obviously capable of giving most accurate results: in fact, with proper manipulation, it is very doubtful whether any measuring device, which has up to to-day been designed, could more correctly sum up passing current. It is in the manipulation and care which such meters require, that their fault lies--if fault there be.
It will be useless for me to waste the time and patience of my kind listeners, by describing to them the eminently successful and generally popular Edison chemical meter, and I will not attempt to do so.
An electro-plating bath in its meter form as generally used, does not, however, give a dial indication, and the consumers ask for a dial indication almost invariably, unless they have already become thoroughly familiarized with Edison meters as used by many large Edison stations.
Many very ingenious and some quite successful attempts have been made to actuate a train of gears by the electro-deposition of an electrolytic bath. Thus, we have two electrodes suspended at the opposite ends of a walking-beam, as shown in Fig. 1. This
walking-beam is in various ways connected with a pole-changer, and as but a sinall portion of the current being measured, passes through the true meter (for of course almost all chemical meters are shunted) the pole-changer is not perhaps a very serious objec
The action of such a meter as this is obvious; we have deposit from one electrode onto the other, until the second electrode becomes the heavier, when the beam tips and the recording device is set one notch ahead, the pole-changer is thrown over, and the deposit takes place in an opposite direction, the former plus electrode becoming the minas, and so on. This device deposits and reposits the same zinc, or rather electrode material. Again, we have a modification of the same device in the form of a wheel bearing a number of electrodes, and on the same principle setting up continuous rotation.
1. See Jenks on the Edison Chemical Meter, TRANSACTIONS, vol. vi., p. 26. 2. See also, TRANSACTIONS, vol. vi., p. 32.
It should be noted, that in this first digression from the chemical meter, we at once meet with the prime factor of difficulty in all motor meter construction—that of friction, which, if uncompensated, must invariably introduce more or less serious
We shall touch on this point more fully hereafter. Another form of self-registering electrolytic meter has a cathode plate suspended from a spring-balance, an ordinary sensitive spring weighing machine, and the heavier the cathode grows, so much greater is the registration of the spring indicator. This device is perhaps preferable to the reciprocating movement just described, but is limited in the capacity of the spring, and probably lacks sensitiveness to small amounts, being dependent of course solely upon the nicety of construction in the springbalance.
Mercury has at times been employed in the construction of electrolytic meters, and with at least moderate success, for with a mercury, anode and a cathode of the same or other material, a record easily measured may be obtained, and such a meter may even be made self-registering in a graduated tube or by half adozen other more or less simple means.
Such are the more typical electrolytic meters. There are other similar devices which have not been mentioned, for it is absolutely impossible to deal with everything within the brief limits of a single paper.
Another form of chemical meter formerly quite popular among inventors, depended for its registration upon the decomposition of water, generally acidulated water, and sometimes upon the decomposition of more volatile substances. This class of meter may very properly be divided under two heads :
First, are those meters simply dependent upon the measurement of the gas developed by the decomposition of water through any gas registering device. We may say that such meters are mere decomposing baths connected to a gas meter. There are some devices of merit which may be classed under this head, but the principle is probably not commercial, for we have nothing very successful of this kind in use to-day.
One of the more ingenious meters of this class provides a diagonally placed rotating wheel with pockets; the decomposition takes place directly under each pocket progressively, and as the air pocket fills with gas, the wheel rotates sufficiently to free this gas at the surface of the fluid, bringing another pocket into place. Others have a rising and falling diaphragm like the popular gas meter, and still others, a delicately poised air fan over a minute aperture.
This last device is obviously most inefficient.
The second group of meters under this classification brings us to the thermo-meters; a typical group containing a few meters of more or less pronounced merit.
Those thermo-meters depending upon volatilization of a fluid, generally have two or more sealed bulbs partly filled with some volatile fluid, as for example, naphtha or ether. When two such bulbs are used, they have generally been mounted on a walkingbeam mechanism combined with a pole-changer; each bulb containing some kind of a rheostat or heat developing device de pendent for its heat on the current passing through the meter, the two bulbs communicating with one another. The rheostat in but one bulb is in circuit. The heat developed in the rheostat in circuit, volatilizes more or less rapidly the fluid contained in this bulb, according to the current passing through it. The gas developed either passes in gaseous form into the second bulb and condenses, or else, as is more common, forces the fluid remaining by the simple increase of pressure into bulb No. 2, which at once becomes heavier and causes its end of the beam to fall. This throws the pole-changer, and the rheostat in the second bulb is thrown into action, repeating the operation as just described. To be successful, such a device must be very sensitive, and to be sensitive, the construction must be of a more or less expensive character, and so delicate as to be to a greater or less degree prohibitive. Like the walking-beam meters just described, instruments of this class have been designed with a number of bulbs mounted on a rotating wheel; the same actuating principle holding true for all such devices.
Another ingenious form of thermo-meter, no longer in any sense a chemical meter, is an instrument dependent for its action upon the heat in a contined but circulating atmosphere. Thus a rheostat dependent for its heat upon the amount of current passing, is so arranged as to heat a body of air, which, by the peculiar construction of its receptacle, at once commences to circulate more or less rapidly, dependent upon the heat. It is obvious, that if a delicate air fan, a screw propeller in fact, be suspended over such a column of circulating air, its speed would