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suggests a polyphase system. In the character of the currents that flow through it, and in the distribution of the energy, it is peculiarly single-phase in its character. I was interested in Mr. Scott's remarks on the subject of the four-wire connection of the two-phase; and, in the second place, the three-wire connection of the two-phase system. Now, with a four-wire connection, it is, of course, possible to use the Edison three-wire system on each branch, if one so desires; but, in order to do so, and to run motors at the same time, one must interlink the two three-wire systems; in other words, you must have two three-wire systems, each system being approximately balanced as to itself, and each three-wire system balanced as respects the other three-wire system occupying the same territory. They must be interlinked for motor service, and that is the reason which, I maintain, bars out the two-phase, four-wire system from employing the Edison threewire connection, just as it must bar out in the same way, and even more effectively, the three-phase system from operating on each of its three phases an Edison three-wire system. It makes a complication of circuits for general distribution that would be perfectly intolerable, two three-wire circuits in the same territory, and each balanced with respect to the other-it would be something better imagined than described. In certain cases, for lights only, it may be applied, because you are at liberty to scatter your circuits; but even then it would require more or less. balancing of the two systems, else you get into trouble with one side of the machine having a greater load than the other, which causes a difference in drop that cannot be compensated by compounding. With the two-phase, three-wire system, Mr. Scott's point was well taken on the question of maximum
voltage. However, if you are dealing with the maximum permissible on the transmission line, where the thing to be considered is not the maximum on the distributing system to translating devices, but the maximum permissible on the whole system, and if you confine yourself to that, you will find that combining the two-phase into three wires requires excessive copper. If you confine yourself to the secondary system alone, it will be possible to permit the same maximum voltage as on the straight Edison three-wire, and I should say that the same rule would apply to the reduction of copper in the three-phase, three-wire system, or any other systems, in varying degree, according to their character.
As regards the question of unbalancing, I think I stated with a fair degree of distinctness that with any polyphase system, though unbalancing may occur, and occur in a serious degree, I do not believe it would be a common occurrence. I think I specifically included the polyphase systems in general.
In the first
With regard to the question of the reduced capacity of transformers operating on three-phase or monocyclic systems: As a matter of fact there are three plans of working, we will say, with a threephase system as regards its transformers. place, we may have a composite transformer, including all three legs of the circuits, which has been used with very fair results; next, we may use three transformers, or finally, only two transformers. Sometimes it is more convenient to use three, and sometimes two. We must remember that there are not to be had an indefinite number of sizes of transformers, nor an indefinite number of sizes of motors. The consequence is that it is sometimes a difficult matter to find transformers that will exactly
fit a given horse-power of motor, and the loss of capacity which is thus met in furnishing transformers too large for the motors (because we must be sure to have them large enough) may easily amount to ten or fifteen per cent either with two or three phases; and unless special transformers are made to fit the motors, we are liable thus to require an increased total capacity of transformers, as well on two-phase as on three-phase systems. With the three-transformer connection for the three-phase circuit, we have one very material advantage which, perhaps, makes it worth while to employ it in many cases, and that is, that if one of the transformers is for any reason crippled, we can operate at least two-thirds of the output with the remaining two; whereas on the two-phase system, if one transformer gives out the motor is crippled, either by overloading and stopping absolutely, or is able to run only at half output as a single-phase motor, but in no case starting until the transformer is fixed. If two transformers are used, the statement has been made that the loss in output in connecting threephase transformers is about sixteen per cent. I should like to see experimental evidence brought up in this case. We have been informed in many well written technical articles that the output of the polyphase machine was thus and so in connection with a single-phase machine, and we know that the facts do not fully bear out the theory. We are now given similar information in regard to the transformers. While I am not prepared to dispute the facts without having experimented on it, I should like to to see some evidence that the difference in output rises to any practical magnitude.
As regards the teaser transformer, I think
may consider the secondary transformer on the monocyclic three-wire system as practically a part of the power wire. It needs to be of small size, and furnishes only a small amount of energy. With that connection, the one transformer furnishes the power wire for the whole three-wire system. It is not a part of each motor, but simply a part of the power wire; and as such, it may be taken as a part of the installation belonging to the three-wire system. The single small transformer in the system furnishes the entire power wire for the whole system.
As regards the motor on the monocyclic two-wire system, it is correct, in a sense, to say that the motor does not know whether it is on a three-wire circuit or a monocyclic. As regards its operation, it does know; that is, as regards the directions of the electro-motive forces in it. It is a matter of perfect indifference which system it is on; but as regards the character of the currents, and their direction, if the motor possessed an ammeter to put in its own coils, it would find that there was a very large difference in the distribution distribution of currents. As regards its magnetic qualities, it would not matter, although the actual distribution of the current is widely changed. We have in the monocyclic induction motor a motor which in its operative qualities is like a polyphase motor. Nevertheless, the distribution of currents in it, although resulting in a perfectly symmetrical production of motive power, is something that you cannot find in any polyphase motor. It depends on the particular action used in the monocyclic system. It has essentially a single-phase current, although its effect as regards magnetism is closely similar to that of the true polyphase motor.
As regards the motor on the monocyclic three
wire system, I was much pleased with the ingenuity with which Mr. Scott constructed a large, ablebodied and well-dressed man of straw for the purpose of knocking the gentleman down and jumping on him with both feet. The motor is not a two-phase
motor of any kind.
It is an ordinary induction
Doubtless, from the
realized how The winding respect similar There is a
motor, such as is used indifferently on three-phase or monocyclic systems. experience of the speaker, he deeply bad a bad two-phase motor could be. of the monocyclic motor is in every to that of the three-phase motor. possibility and sometimes a great convenience in being able to work a monocyclic generator as a synchronous motor. Used in such a way, it works during its operation like any other synchronous motor. It is a possibility which is sometimes very convenient; the motor starts itself, and the teaser coil, when the motor is up to speed, produces no effect on the rest of the system, if the motor is properly designed with reference to suppressing the electro-motive force of the teaser circuit. In the monocyclic three-wire system, we have in the first place a three-phase motor structure, but operating on a monocyclic three-wire and teaser circuit, with the properties and distribution of currents-or electrical character of the single-phase system. The actual details of operation in a monocyclic motor are somewhat complicated. Substantially, we have a structure which is in all its characteristics only proper to be operated on the monocyclic or three phase circuits. The currents which flow througa it, however, are not three-phase currents, the electromotive forces, however, being 120 degrees apart. The currents are substantially in phase, but the