GB555021A - Improvements in or relating to electric circuit breakers - Google Patents

Abstract

555,021. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. May 4, 1942, No. 5995. Convention date, May 3, 1941. [Class 38 (v)] A three-pole circuit-breaker comprises a contact-carrying lever 97 for each pole pivoted at 33 and carrying a pivoted main contact 53 and arcing contact 59, the poles being interconnected by a bar 35. The breaker is retained by a linkage comprising a compound overset toggle 109, 111, 123, the latter lever having a fixed pivot 127 and being connected by pivot 137 to a further toggle 126, 128, the lever 128 having a fixed pivot 129 midway of its length. The latter toggle is in turn retained by a further, trippable, toggle 131, 133 which is pivoted at 145 to lever 128 and is held overset against a stop 163 by a spring 165 anchored between the fixed pivot 156 of lever 133 and a part 147 of lever 131. This toggle can be tripped either by an over-load or tripping plunger 167 engaging a part 159 of lever 133, or by manually engaging an extension 205 on part 147 of lever 131. When tripping occurs, levers 128, 123 rotate about pivots 129, 127, respectively, under the action of the opening spring 161 assisted by the contact springs 69. 73 At the end of the opening movement, the toggle 109, 111 breaks downwards, thus causing the rest of the linkage to reset itself. Reclosure is effected by a lever 171 which is pivoted at 127 and carries a roller 177 engaging the toggle-knee to restore toggle 109, 111 overcentre, whereupon a spring 181 returns the lever 171. The latter carries a roller 201 for engagement by a manual reclosing means, and is additionally formed with a surface 221 for engagement by electric motor-actuated reclosing means. The first-named comprises a handle 183 rotatable about an axis 191 and carrying an arm 193 to which is pivoted a depending lever 195, the end of which engages the roller 201, whereby clockwise rotation of the handle through 90 degrees effects reclosure and the handle is returned to verticle position by spring 181. A slight movement of the handle 133 in the reverse direction, Fig. 2, causes a lug on the lever 195 to engage the extension 205 for manual tripping, the movement being performed against a strong spring 207 which prevents undesired tripping by vibration or when the handle is restored by spring 181 after closure. The trip plunger 167 is operable either by a shunt trip coil 235 or by the centre arm 261 of a number of arms on a common trip shaft 263, the arms 261 being each engageable by the armature structure 251 of the appropriate series trip device comprising a core 239 surrounding the strap 15. The motor closing-device comprises a motor 211 driving through reduction gearing a crank disc 217 carrying a roller 219 which is caused to make a complete rotation in the course of which it engages the surface 221 which is shaped so as to move the breaker-arm quickly at first and later to spread the final closing movement over a substantial part of itself, thus, in combination with the arrangement of toggle 109, 111 easing the closing duty. The motor closing-unit is readily detachable from the framework supporting the linkage as is also the arc-chute structure from the base so allowing easy access to the contacts.