The Works Of Messrs. Schneider And Co.

THE ELECTRICAL CONSTRUCTION DEPARTMENT. 117 to packing, tor which watertight cases are used, and each machine is delivered with a detailed statement giving the tests it has undergone and the instructions for its working. The Central Lighting Station. Messrs. Schneider and Co. commenced lighting tlieir Creusot Works with arc lanips 20 years ago, and, since tliat date, gas lighting has been gradually superseded. At first, direct-current dynamos were placed on the spot where the current was needed, and near the boilers and engines belonging to the varions departinents. In 1891 there were at the Creusot Works, several direct and alternating current installations, which represented a total of about 150 horse-power. At that time it was decided to light the new hospital, then in course of construction, by electricity, and a large central station was designed for generating the energy necessary to light both the works and the hospital. Owing to the great area to be dealt with, Messrs. Schneider and Co. decided upon an alternating system with a 2,000-volt current, and with transforming sub-stations placed at the main points of utilisation. In 1893, when the engine-room was erected, the necessary provisions having been made for future extensions, two elcctrical groups, one of 100 horse-power and one of 300 horse-power, were put down. The amount of current required was, however, under-estimated, and the following year anotber group of 300 horse-power was installée!; whilst in 1897 the original 100 horse-power group was replaced by a third one of 300 horse-power. Besides these three groups which serve for eleetric lighting, the station containstwo sets, consisting each of a single-cylinder steam engine of 125 horse-power and a direct-current Ganz dynamo, which supplies current at 220 volts to the eleetric travelling crânes of adjacent shops, and a third set of the sanie power, consisting of a steam engine similar to the above, and a two-phase gene- rator, formed of two connected Ganz dynamos ; this plant supplies current to the motors in the electrical department sind laboratory ; these are about 1500 metres (about 1 mile) distant from the central station. The boilers employé«! are of the tubular type, and are heated very econoinically with the waste gases from the blast-furnaces. The arrangements of tlie works did not allow of placing the steam engines near the boilers ; it was necessary, therefore, to provide about 200 metres of overhead piping to bring the steam to the central station. The resuit îs a rather heavy drop of steam pressure ; owing, however, to the economical way in which the boilers are heated, the arrangement, as a whole, is advantageous. The steam engines are of the Creusot compound type, horizontal, with two cylinders, and steam jacketed. These engines drive direct on the dynamo shaft. Steam is distributed by cylindrical balancée! valves, worked by eccentrics, which are driven by cranks at the ends of the main shafts. The low- pressure cylinder eccentric is keyed to the shaft, that of the high-pressure cylinder forms part of a speed regulator, with centrifugal weights that act on the expansion gear of the liigh-pressure cylinder and modify the throw of tlie eccentric. These machines run at 160 revolutions, and develop 300 horse-power, with an initial pressure of 7 kilo- grammes (99.56 ll>. per square inch) in the high-pressure cylinder. The variation of speed between the working with no load and with füll load, reaches 6 per cent. The dynamo of each set is an alternating-current single- phase Ganz machine, the frame of which is bolted to the engine bedplate, and between the two cylinders, so that the revolving fiele! magnet is in the axis of the bedplate, and is mounted on the main engine shaft. The field magnets which re volve within the fixed armature ring are supplied with a low-tension direct current by means of rings revolvino1 on the shaft against fixed brushes. The field magnets are built of thin plates with 32 radiating arms, each carrying a coil, the frame being mounted on a cast-iron centre keyed to the shaft. The main frame of tlie alternator consists of two cast-iron rings carrying the fixed armature, with as many coils as there are pôles in the field magnet. All of the coils are so mounted and fixée! that they are interchangeable, and are easily renioved for repairs, and as easily replaced. The armature coils are grouped in series, and the ends of the armature circuit are brought to two primary terminais, placed on a protecting cover at tlie bottom part of the alternator. The fixed part of the alternator is easily removed to facilitate the inspection of the field magnets. Tlie cxciting current is furnished by a dirGct-curront four- pole dynamo, placed on an extension of the shaft, and driven by an elastic clutch. The switchboard of the generating dynamo is somewhat similar to that used at the Decize Mines, already referred to. The current régulation is effected by means of an automatic field rhéostat on the Ganz system, which acts on the exciting dynamos. Coupling in multiple is regulated from a phase indicator, fornied of incandescent lamps, which are extinguished as soon as synchronism takes place. Above the switchboard is a charge rhéostat, which is used to bring up an alternator to its füll output before connecting it in multiple with anotber then inwork. Two main lines, one 500 metres and the other 1400 metres long, start from the switchboard bars, and are extended to the two ends of the works, supplying current to the primary mains, which correspond to the varions transforming stations. The main and secondary lines are uninsulated, carried on iron standards, fitted to the roofs of the varions shops. The main that supplies current to the south-east partof the works is placed underground for part of its length. This main is fornied of aconcentric arnied cable, 150 metres long and 50 square millimétrés (0.078 square inch) section, laid in a conduit .500 metre (19-J4 in.) deep. Beyond the part where it crosses the telegrapb wires, the line is aerial and branches off in several directions to supply current to varions shops and to the hospital ; the latter can absorb a maximum of 20 kilowatts, and the distance from its junction with the main is about 1500 metres (about 1 mile). Each department is provided with a switchboard con- sisting of a glass frame, containing one high-tension double- pole ■ lïiake-and-break, one Blathy meter for alternating