Bus duct plug

• Main Authors: SLICER ALLAN E, JORGENSEN GEORGE N
• Format: Patent
• Language: English
• Published: 29.08.1967
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION; INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINEDOPTICAL AND ELECTRIC CABLES OR LINES

1,143,603. Switchgear structures. SQUARE D CO. 24 Jan., 1967 [14 April, 1966], No. 3631/67. Heading H1N. [Also in Division H2] A bus duct plug, which as shown is for use with a three phase, four wire system, comprises a box 22 whose front wall is a hinged cover 24, switch blades 36 within the box being movable, by means of handle 98 outside the box, from OFF to ON positions to connect load terminals 62 through fuses 64 to stationary contacts 48 and thence via conducting straps 43, 44, 45 extending through the rear wall 22b of box 22 to plug-in jaws 40 which grip bus bars 42 of bus duct 26. To connect the plug, it is hooked on to the duct 26 by hooks 108, 109 and screw 110 (see Fig. 2-the left, or handle, side elevation, and Fig. 4-bottom plan, and also Fig. 8, not shown) is turned to move member 116 to the left in Fig. 2, rotating locking member 122 whose arm 122a is slotted into 116, and raising it since its arm 122b is located in an oblique slot (Fig. 10, not shown), locking member 122 being loosely pivoted to bracket 120 at 124. As it rises, bent up end 122e of arm 122c bears against a portion of the duct 26, and jaws 40 are drawn on to bus-bars 42. The plug cannot be withdrawn when the switch handle 98 is in the ON position (full line in Fig. 2) since interlock member 102 prevents movement of screw 110 to release locking member 122. Further, with switch handle 98 in the ON position and screw 110 in the clamping position, bent over end 122d of arm 122b interferes with the duct housing if an attempt is made to plug in. Interlock member 102 also prevents the switch handle being turned to the ON position when screw 110 is in the unclamping position (broken line in Fig. 2). The switch blades 36 are actuated by a bail member 66 (Fig. 3), one end 66a of which pivots on the bottom wall 22c and the other flattened end 66b pivots on a pin 70 supported by top wall 22d and a wall of channel-shaped bracket 72. A drive cam 78 (see also Fig. 6, not shown) drives an operating member 76 connected to bail member 66 with a snap action at the limits of its pivotal movement by an overcentre spring 86. Arm 78d of the drive cam has a pin 90 riveted to its end, this pin being received in a slotted short leg portion of L-shaped driving lever (92) (Fig. 7, not shown), the long leg portion (92b) pivoting on pin (94) in the left side wall 22e of the box 22. Lever 92 is driven by pin 96 extending through a slot (92c) in the lever and through arcuate slot (22f) in wall 22e and connected to handle 98. A bent-over portion of driving cam 78 engages a latch in cover 24 when the switch is in the ON position to prevent the cover being opened.