Motion Picture News (Sept-Oct 1916)

2728 ACCESSORY NEWS SECTION Vol. 14. No. 17 A B C of the Motion Picture Projection Room Difference Between the Fort Wayne Direct Current Conipensarc and the Compensarc Made by the General Electric Company— One Machine. Operates as a Motor, Taking Its Current from the A. C. Supply Lines and the Other Is Used with Alternating Current and Generating D. C. Current (Continued from Last Week.) THE device to be illustrated this week is what is known as the Fort Wayne Direct Current Compensarc. Do not confuse this as so many operators do with the "Compensarc" manufactured by this branch of the General Electric Company, known as type A. The similarity of names has caused many op Plate I. erators to confuse the two, but the type A, was and is an A.C. Compensarc, while the one accompanying this article is a D.C. Compensarc and consists of two machines united together on the same shaft. One machine operates as a motor, taking its current from the A.C. supply lines, and driving the other machine as a generator to furnish current at the lamp. A combination of machines such as this is generally called motor-generator sets, and though the Fort Wayne Direct Current Compensarc for a 50 volt circuit is a motor generator set, the 115 and 230 volt sets are not, since the electrical connections between the machines are different from those in a true motor-generator set. I do not believe it necessary to show the windings for the two sets since an operator will seldom if ever be called upon to use anything over the 230 volt set. Plate 1 shows the Compensarc itself, and you will note that the frames of the two machines are bolted together making it unnecessary to have a specially constructed base for mounting, and since there are no belts, gears, etc., needed the machine can be installed in the operating room or a room adjoining where it will be out of the way. Fig. 1 shows a wiring diagram for the connecting of a one lamp 50 ampere set, for either single phase, two phase or three phase. While Fig. 2 is the wiring diagram for a set designed to operate two lamps alternately, this drawing also shows the connections for single, double or three phase. A careful study of these drawings will enable the operator to keep things running in first-class shape and if the wiring is of suiScient size and the carbons have the correct polarity, that is, the upper positive and the lower negative, there is no reason why the operator should not be able to do so. Bolted to the frames of the machines are the bearing flanges which hold the shaft bearings for the shaft, and the brushes which fit on the commutators and carry the current to the armatures. The bearings have a metal lining of special construction which is self-centering, and are supplied with oil by oil rings which rest upon the rotating shaft and turning with it carry oil from the large oil well, located in the bearing flange just below the bearing, up to the top of the shaft. Both bearings have an oil gauge which enables the operator to see at all times the exact amount of oil in the oil wells; a little cover is also placed over the top of the bearing so that the operator can also see if the oil rings are working properly and giving proper lubrication to the machine. The armatures of the motor and generator are both mounted on the same shaft, and each has its own commutator. The brush yoke, carrying the brushes, is mounted on the bearing flange and Line. View ^/roi-i Back of Boakd. Oaie 7 Mo roR. ^ Fuses Sox bearing against the rotating commutator completes the circuit between the armature and the line. The revolving fan, which is mounted on the shaft between the two machines, and which revolves with the shaft setting up a current of air that keeps the machines cool is surrounded by a metal guard; this guard being perforated to allow of sufficient ventilation, and also protecting the operator from any injury that might result from his coming into accidental contact with it which might happen were it not so guarded. Care should be taken to install the Compensarc in a dry, well ventilated place ; a place as free from dirt and dust as possible, for it is dirt that causes the most trouble with any machine, and it is just as easj' to keep your apparatus clean as it is to allow it to become so badly caked with dirt that you have to spend hours in getting it in condition again. The operation of the Compensarc is as follows : See that your carbons are separated ; taking for granted that your fuses and connections are O. K., then throw in the main switch, when the armature will start to rotate. Then move the lever of the starting box to the right, slowly, as the machine speeds up, until it reaches the last contact point, when it will be caught and held by the cut-out magnet. When the machine has reached the limit of speed and is operating properly, you may adjust the voltage by moving the knob on