GB472250A - Improvements relating to electro-magnetically operated mercury switches - Google Patents

Abstract

472,250. Electromagnetic interrupters. CIANCHI, A. Jan. 20, 1936, No. 1849. [Class 38 (v)] An electromagnetic interrupter of the type comprising a vessel containing a magnetic plunger the extent of immersion of which in mercury or other conducting liquid being varied electromagnetically and the consequent displacement of the surface of the mercury causing it to make or break connection with one or more contacts has such contacts contained in a branch of the vessel into which the conducting liquid flows to make contact when the plunger moves down and out of which it flows to break contact when the plunger moves up, the switch formed by the contact or contacts in the branch and the liquid being connected to the electromagnetic means for moving the armature so that the switch is caused automatically to make and break contact repeatedly and the vessel is mounted so as to be capable of being tilted to vary the frequency at which contact is made and broken. As shown in the Figure, the main interrupter comprises a receptacle 3 containing mercury which normally touches a contact 6 but does not reach contacts 9, 10 in a side-passage 8. When the cylindrical armature is drawn down however by energization of the coil 11 surrounding the container the level of the mercury rises to the contacts 9, 10 but contact is not immediately established between them and the contact 6 as a ball valve 13 is forced against a seating consisting of an insulating liner 12 so that mercury in the armature is temporarily drawn down from the contact 6. Mercury, however, leaks past the valve through a restricted passage 14 so that after a slight delay contact is established through the mercury and the operating coil is short-circuited. The armature is then free to rise, its upward movement being unimpeded as the ball 13 is then forced off its seating. In the arrangement shown a circuit from the self-interrupting switch 3 at contact 10 controls a second mercury interrupter in a vessel 3<1> which in turn controls the load circuit. Both of these interrupters are carried on angularly adjustable bases so that the time taken for the mercury to reach contact 9 may be lengthened or decreased and the frequency of interruption can consequently be varied. In a modified arrangement the tilting of the base is effected through eccentric mechanism. Specification 453,229 is referred to.