[NM021AAG], Technical Note, Thomas Alva Edison, October 20th, 1887


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[NM021AAG], Technical Note, Thomas Alva Edison, October 20th, 1887

Editor's Notes

The object of this invention is to diminish the amount of copper in the distributing system of Central station Electric Lighting so that large areas can be supplied from one central station without the use of large amounts of conducting material and without the intervention of apparatus wasteful of energy. The direct connection of the translating devices The consumption of energy being in proportion to the number or size of the translating devices. In previous patents Nos ______ I have shewn a method in what is called the 3 wire system whereby the two sides of the system are balanced by causing automatically or by mechanism controlled electrically from the Central station, a gropu of Lamps to be thrown over from one side to the other, so that if it is found that one side has more lamps on than the other a definite portion may be disconnected from overloaded side & fed from the light loaded side so as to effect a balance in the patents spoken off-- The present invention is an extension of the same idea & more applicable to Large & very extended systems of distribution and on 4, 5, 6 or more wire systems. It being essential in any extension of the 3 wire systems to a 4 5 or more wire system that the balance should be very even as above a 3 wire system the difference of pressure due to out of balance is in certain conditions not regulable by varying the resistance of the feeders and as it is a great saving to use very small neutral wires in the feeders it is necessary that the balance should be such at all times that only a comparatively small current shall ever pass through them. Hence it is essential that in a large area a large number of groups at different points should be capable of being connected to any circuit without running a great number of separate circuits to the switching mechanism-- The invention consists in placing a number of boxes throughout the district containing the switching mechanism each controlling all the lights in a certain house or store. The boxes are placed preferably in the poles like fire alarm boxes-- Each box has two electro magnets, one large the other small-- If there are 20 boxes a circuit of ordinary telegraph wires runs from the station through all the samall magnets. Fig 1 another circuit runs through all the large magnets, the 2 extreme ends are connected to the outside wire of the system, at the station there are two dials C C' worked by magnets, 2 keys K K' serve to open & close the circuit. R is an adjustable resistance. The two circuit join & are connected to the other side of one dynamo thus giving 100 volts to each circuit. Fig 2 shews the sweitching mechanism a is a ratchet wheel with a greater number of teeth than there are boxes on the circuit-- di the click H the magnet lever K the retractible spring L the limiting screw N the small magnet, n the back lash click c the locking click stop. On te shaft carrying the ratchet is a disc 6 with a notch Q The notches in each disc in every box is in a diferent part of the periphery of G except at one point where the M' mechanism is to be [unwound?] f is the unison arm I the unison stop pin-- M is the unison releasing arm connected to the lever S of the large magnet M' Thus if the Operator at the central station taps the key of the small magnet circuit a number of times the rotation of the Ratchet shaft will cause the coarse screw to advance the unison arm up to the unison pin & stop further rotation-- now by depressing the key of the large magnet circuit once the arm M throws the arm f upwards & a spring pulls it back to the other extreme of the screw on the shaft thus all the Ratchet mechanism controlled b M in every box can at any time be brought to a definite point & be in unison-- When in unison there is no notch oppose R on S in any box-- but there is sufficient space for R to work from its position of rest to the peripery of the wheel to trip the unison mechanism Having brough all the M mechanism to unison-- The M' mechanism can be brought to unison, the disc may be advance to such a position where the notch Q is opposite R of every box The large magnet circuit is now worked ans as T' is a similar unison the lever T will soon reach the unison stop pin & stop further rotation on work M the lever p of H relaeases the unison & both magnetic systems are in unison. Supposing all the boxes have both mechanisms in unison, the customer or house are connected [perniscously?] among the boxes No 1 box when in unison has the house on No 1 circuit No 2 box on No 2 circuit & so on so that in practice the houses will be connected to balance each other when the mechanisms are all in unison at one point. About 1 box for every 15 houses will be enough in practice ie 10 lights controllable will balance every 150 lights uncontrollable. 3 is the switch ratchet, Y the click 1 & 2 are rings one ring connect to spring 4 & one to spring 4' The spring being split around the shaft so that the two halves are electrically insulated from each other-- on these rings. Rub two springs W. V. wires from these springs pass to the house where the lamps or other translating devices are counnected in multiple arc-- 6 to 12 are contact plates on a insulating disc 13. These plates are connected to the 5 wire system as shewn in fig 3. by the rotation of the switch shaft the group of Lamps on W. V. are successivley thrown on the 4 circuits, by advancing 4 points, owing to the use of an electrolytic meter The othe rhalf of the revolution cannot very conveniently be be used hence to bring the group of lamps back to the 1st circuit the mechanism is not allowed to rest on the other 4 plates but the arm 4' is brought back to the original positions fig 4 shews the box on the pole 1 2 3 4 5 are the wires of the 5 wire balance system X X are insulating pieces in thecircuit to cut in the large & small magnets in circuit, 8 & 9 are pressure wires-- etc-- fig 5 shews unison mechanism & [disc?] 6 with notches in different positions Now supposing the system balanced & all mechanisms of boxes at unison-- ampere meters fig 1 on neutral wires shews no current, now supposing a consumer shuts off his lights on circuit No 1 the balance is destroyed & a current passing through one ofhte neutral wires to station deflects the amperemeter & shows say 30 lights-- or several customers whoses aggregate amounts to 30 lights have shut off-- The Regulating operator, looking at his dial C & C' fig 1 works the key and working the mechanism previously described disconnects by 2 or more boxes sufficient lamps from the other 3 circuits & connects them to circuit No 1 to balance the system which is immediately apparent to him by the action of his amperemeter This mechanism can be used to disconnect contract customers feeders at a distance, Transformers & in fact every kind of apparatus I do not which to confine myself to putting the boxes in series as all the small magnets may be worked in multiple arc on one ckt & the large mags ditto-- in fact both magnets may be polarized & put in or across one circuit & a current of one polarity intermitted work one magnet & the opposite current intermitted work the other magnet. Instead of the keys a rotating transmitter with break wheel & dial may be substituted. The feeder as a whole has its general pressure regulated by feeder regulators in the ordinary way-- Claim the Earth--




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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