| 摘要 |
A rectangular metal shell (36), with continuous flanges (54,56) around its sides and ends, supports a switch operating shaft (22). This carries on insulators three sets of contact arms (28) terminating at each end in twin-blade knife-edge arrangements (30). The shell is closed, top and bottom, by moulded bolt-on (58) insulating caps (38,40) each incorporating three separate conical sections along their length. These cones support inserts (18) with solid contact ends (14) and have helical insulator fins (68) disposed outside around each. Each pole of the switch has associated internal earthing arrangements (70,72) which link one row of inserts (20) to the frame (36) on selecting on intermediate shaft position. An inspection window is provided for checking contact position and operation. ADVANTAGE - Central metal shell and insulating closures allows advantage of gas filling to be obtd. without problems of sealing and assembly encountered in other structures.
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