GB629748A - Improvements in contact arrangements for air-break electric switches - Google Patents

Abstract

629,748. Air-break switches; switch contacts. PAROLLE ELECTRICAL PLANT CO., Ltd., and ANDERSON, E. Nov. 15, 1947, No. 30359. [Class 38(v)] An air-break isolating switch has a moving rocking contact member which cooperates with a dihedral member forming the stationary contact. The moving contact head 6 of the isolator is mounted on an insulator 5 forming part of a pivoted switch arm indicated at 3. Projecting from an opening in the contact head 6, is the rocking contact 7 which has a recess 7a engaging the end of a cantilever leaf spring 8, and abutments 7b, 7c engaging corresponding abutments 6a, 6b in the contact head when the switch is open. To close the switch.the arm 3 is swung downwards towards the dihedral contact member 2 and the end of the contact 7 at first engages the lower limb of the contact 2 as shown in Fig. 3. Further movement of the arm 3 causes the contact 7 to pivot about an axis formed between the abutments 7b, 6b, and the end of the contact 7 slides up the lower limb of the fixed contact 2 until it abuts the upper limb. When the switch is completely closed, Fig. 5, the lower end of the contact 7 is supported on the spring 8 only, the spring 8 being fully stressed. The movement of the contact arm 3 may be sufficient to carry the pivoting axis y of the contact 7 beyond the line x connecting the point of contact between the fixed and moving contacts and the pivoting axis of the arm 3, so that an overset toggle is formed which automatically holds the switch closed. Each limb of the contact 2 may be bifurcated. It is stated that the construction permits the use of a strong spring giving high contact pressure facilitating the shattering of ice formation.