SWITCHING EQUIPMENT 



581 



tionary contacts are the same as those used on H-type oil circuit 

 breakers. 



When the switch is opened a flange near the tip of the blade 

 prevents the blade from dropping below the upper part of the lower 

 stationary contact. A wide 

 flare on the lower end of 

 the upper contact leads the 

 blade into place when the 

 switch is being closed. 



After the blade is closed 

 a slight turn to the right or 

 left by the operating rod 

 locks the blade in position 

 and prevents it from open- 

 ing except when desired. 



Sometimes the discon- 

 necting switches are wired 

 up to indicating lamps 

 mounted on the control 

 switchboard. These lamps 

 are then inserted in the 

 miniature bus-connections 

 and will show to the oper- 

 ator whether the switches 

 are in the open or closed 

 position. 



The switch shown in 

 Fig. 374 is for use on 

 heavy outdoor service. All 

 the three poles are operated 

 simultaneously by a lever 

 or handle which can be located at any height from the ground 

 and locked in either open or closed position. It is of the single- 

 break type, equipped with a horn-type arc deflector on the sta- 

 tionary contact. The shape and location of the horn in conjunc- 

 tion with the upward movement of the switch blade definitely 

 confines the arc on rupturing the exciting current of a line to the 

 horn and blade and quickly ruptures the arc without short-cir- 

 cuiting the line or involving adjacent apparatus. In operating 

 the disconnecting switch the blades move in a vertical plane 



FIG. 373. Special Disconnecting Switch 

 for Restricted Quarters. 



