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Show MOTOR GENERATOR DIFFESRENTIAL COMPOUND Magnetizing Action in Two Fields Cumulative Compound Com-pound Reasonable Value Val-ue of Voltage Generator Gen-erator Outfit. (By special permission from Motor Age.) The compound moior is a combination combina-tion of the series and shunt. When the magnetizing action of the series field opposes the magnetizing action Of the shunt field the machine is called a differential compound motor. When j the magnetizing action of the two fields act. in the same direction the machine is called a cumulative compound com-pound motor. The motor generator is a combination combina-tion of a motor and a generator, mechanically me-chanically connected together and usually usu-ally mounted on a common metal cr wooden base. The motor of such a combination may be either a direct current or an alternating current motor, mo-tor, and it may b. constructed to operate op-erate on any reasonable value of voltage, volt-age, depending on the particular requirements re-quirements Likewise, the generator may be one capable of delivering either ei-ther direct current or alternating current, cur-rent, and this current may be delivered deliv-ered at almost any voltage, depending on the requirements, which determine the construction of the generator. When the two machines are coupled directly together by a flexible coupling their speed will be the same. If a belt or gear is used in connecting them their speeds may be the same or different, depending on the size of I the pulleys or gears used. The elec-irical elec-irical operation of the motor is entirely entire-ly independent of the generator. The 'field of either machine may be varied in strength without changing the field of the other machine. A motor gem ratdr outfit may be used in changing alternating current j at one voltage Into direct current at I some other voltage or vice versa, or it may be used in increasing or decreas- ' Ing alternating or direct current voltage. volt-age. For example, suppose only one j alternating current is available and ou wish to charge storage batteries. The motor element of your motor generator gen-erator should be an alternating current cur-rent motor of such a construction and voltage that it will operate on the alternating al-ternating current circuit from which you are to obtain the electrical ener gy. The generator element should be j of such construction that it will deliver de-liver the required current and at the proper voltage. The horsepower capacity ca-pacity of the motor always should be ! such that it will drive the generator when the generator is delivering its full load. In some cases direct current is available, but at such a voltage that it cannot be used economically in charging storage batteries unless the batteries be connected In series, which is quite inconvenient and oftentimes ! impossible. In such cases it often re-, re-, suits in a large saving to install a motor mo-tor generator set composed of two direct di-rect current machines, the motor being be-ing constructed to operate on the volt age available and the generator to deliver de-liver current at the proper voltage to ! charge the batteries. Remember that I the output of the generator in watts I would be equal to the input to the mo-I mo-I tor in watts if there were no losses in I the machines. That is, if the voltage of the generator is less than the volt- age of the motor, then the current the generator will deliver will be greater than the current taken to operate the, motor. On account of losses in the two machines the output of the generator gen-erator is always less than the input 1 of the motor. Dynamotor. The dynamotor is a machine having hav-ing an armature with two windings which may be mounted on the same or opposite ends of the armature Both of these windings revolve in the' same magnetic field, and any change i in the strength of the magnetic field! will Influence the value of the voltage' generated in both windings. The, voltage generated in the two windings wind-ings will be the same if there are the same number of turns about'the arm ) ature in each of the windings. If tho number of turns in the two windings are unequal the voltages generated in the two windings will bear the samel relation to each other as exists be i tween the number of turns, the wind-; ing of larger number of turns having the greater voltage induced in it. Both of these windings may be used to deliver current; that is, both wind ings will act as generators when the! armature of the machine is drhen in; some way, an by motor or gas engine One winding may be used as a motor and drive the other winding in the magnetic field, and it will act as a' generator and may deliver current.' The voltage at which the generator! winding will deliver current depends; on the ratio between the number of turns In the two windings and the: voltage applied to the motor winding. neglecting voltage losses in the two windings. The voltage relation i6 fixed fix-ed by the relation of the turns in the two windings and cannot be changed by varying the strength of the mag-! netic field, as in the case of the motor generator, for the following reasons: If the field of the dynamotor be increased in-creased in strength in an attempt to increase the voltage generated In the generator winding there will be a decrease de-crease in speed of the armature, as the necessary counter-electromotive force now will be generated in the motor winding at a lower speed, since the field strength has been increased. This decrease In speed of the armature counteracts the effect of the increase in field strength so far as the generator I winding is concerned, which results in the voltage generated in the generator winding remaining practically constant. con-stant. If the voltage applied to the motor winding be increased or de-j creased there will be a proportionate increase or decrease in the voltage produced on the generator winding. The fixed voltage relation in the dyna- I motor is its chief disadvantage when used in charging batteries, as the current cur-rent sent through the battery must be adjusted by a series resistance rather than by varying the field of the gen- I erator, as in the case of the motor generator. The dvnamotor is used by several different companies in place of a separate sep-arate generator and motor. The elec trical and mechanical connections of the machine are such that the generator gene-rator and motor actions are taking place at different times. |