Fig. 2,796.—Cross section of electrical station showing small traveling crane.
Installation.—The installation of machines and apparatus in an electrical station is a task which increases in difficulty with the size of the plant. When the parts are small and comparatively light they may readily be placed in position, either by hand, by erecting temporary supports which may be moved from place to place as desired, or by rolling the parts along on the floor upon pieces of iron pipe. If, however, the parts be large and heavy, a traveling crane such as shown in [fig. 2,797], becomes necessary.
Ques. What precaution should be taken in moving the parts of machines?
Ans. Care should be taken not to injure the bearings and shafts, the joints in magnetic circuits such as those between frame and pole pieces, and the windings on the field and armature.
Fig. 2,797.—Cross section of electrical station showing a traveling crane for the installation or removal of large and heavy machine parts. A traveling crane consists of an iron beam which, being supplied with wheels at the ends, can be made to move either mechanically or electrically upon a track running the entire length of the station. This track is not supported by the walls of the building, but rests upon beams specially provided for the purpose. In addition to the horizontal motion thus obtained, another horizontal motion at right angles to the former is afforded by means of the carriage which, being also mounted on wheels, runs upon a track on the top of the beam. Electrical power is generally used to move the carriage and also the revolving drums contained thereon, the latter of which give a vertical motion to the main hoist or the auxiliary hoist, these hoists being used respectively for raising or lowering heavy or light loads. In the larger sizes of electric traveling crane, a cage is attached to the beam for the operator, who, by means of three controllers mounted in the cage, can move a load on either the main or auxiliary hoist in any direction.
The insulations of the windings are perhaps the most vital parts of a generator, and the most readily injured. The prick of a pin or tack, a bruise, or a bending of the wires by resting their weight upon them or by their coming in contact with some hard substance, will often render a field coil or an armature useless.
Owing to its costly construction, it is advisable when transporting armatures by means of cranes to use a wooden spreader, as shown in [fig. 2,798] to prevent the supporting rope bruising the winding.