Switchboards for power, light and railway service, direct and alternating current, high and low tension . wouldbe so far as C is concerned if the voltage were low, butinsulation between H and d would still be required, forthe head of d is upon the face of the switchboard, and ifnot insulated from the circuit damage might be done byaccidentally connecting it with some of the If the voltage is not over no the insulating blocks Dand E can be made of marble or slate, and be used alone,but for higher voltages sheet mica should be placed be-tween them and H. In every case it is advisable
Switchboards for power, light and railway service, direct and alternating current, high and low tension . wouldbe so far as C is concerned if the voltage were low, butinsulation between H and d would still be required, forthe head of d is upon the face of the switchboard, and ifnot insulated from the circuit damage might be done byaccidentally connecting it with some of the If the voltage is not over no the insulating blocks Dand E can be made of marble or slate, and be used alone,but for higher voltages sheet mica should be placed be-tween them and H. In every case it is advisable to placea layer of asbestos between the clamps B F, and the blocks 77 Not as good connection. D, and also between these and H, so that the pressure ofthe bolts g g may be distributed over a greater surfaceand not be liable to break the insulators. For the samereason it is well to make the surfaces of D and E cut awayslightly around the edges, so that the pressure may be ex-erted against the center portion. In some instances the conducting bars are sup-ported from the framing of the switchboard in the. Figure way but not as good as those shown before. manner shown in Fig. 34, but this construction, ascan be readily seen, is not mechanical since H is depend-ent wholly upon the strength of the marble or slate slabB. The slab B is secured to the framing A by the boltse, and H is secured to B by the bolts d. As marble andslate are both brittle, it is not safe to depend upon theslab B to hold H, for if the pressure of the bolts e or dshould be so applied as to produce a strain the slab mightbreak and allow H to fall out of place, and in so doing it 78 Possibility of damage. might short circuit some of the other conducting bars andresuh in a serious loss. Since the accidental contact of conducting bars thatshould be insulated from each other can result in the de-struction of the generators, it follows that no construc-tion is proper that is in any way uncertain, and on this
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1906
