Transformer practice; manufacture, assembling, connections, operation and testing

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ... laminations may be hammered. During the building up of the laminations they should be pressed down two or three times, depending on Fig. 121.--Assembly of coils for a shell-type transformer. the size of transformer being built. For this clamping, the top iron frame is usually lowered and forced down with especially made clamps or the regular clamping bolts may be used if the threading on them is sufficient to lower the clamp to the required dimensions; these clamps or bolts may be left in position over night if any difficulty is found in getting in the laminations. In the case of transformers without a top piece or frame, an especially constructed rigid frame of wood may be used. The laminations should be built up to such a height as will permit the core-plate to be forced into position under considerable driving. It is always a difficult matter to put in all of the laminations that come from the factory as special facilities for pressing are available there. After the laminations have been clamped down, the low-and high-voltage leads should be supported and insulated in a right manner; care being taken in supporting the leads to see that they are properly spaced, for if they are placed too close together a short-circuit might occur. At the cast-iron frames, the insulator bushings used for this purpose are held by metal supports to the frame, and at the point where the leads pass through the bushings, cement is used to hold the leads into position. Both the high and low voltage winding end-leads connect to the terminal-board which is located above the assembled coils and core. In the case of oil-cooled and water-cooled transformers all the leads are brought out at the top; usually air-blast transformers have their leads terminate at the base or part at the...