GB476176A - Improvements relating to electrical relays - Google Patents

Abstract

476,176. Mercury switches. CIANCHI, A. June 2, 1936, No. 15451. [Class 38 (v)] An electric switch comprises a vessel enclosing mercury or other conducting liquid, and a body wholly or partly of magnetic material and provided with external magnetic means for acting on the body to change the extent to which it is immersed in the liquid and thus to change the level of the liquid, the vessel being provided with a part into which the liquid flows to bridge contacts when the liquid level is raised, the part being such that it retains liquid to retain the contacts bridged and the switch is mounted so as to be capable of being moved to discharge the liquid from said part and disestablish connection between the contacts. As shown in the Figure, the tubular magnetic armature 3 with an insulating liner 3<1> when attracted downwardly by energization of the energizing electromagnet 4 causes mercury 2 to be displaced into a side limb 6 to bridge contacts 7, the side limb, being formed at such an angle to the container 1 that when the armature is released mercury is retained in the side limb. In order that the switch may be reset and the circuit between contacts 7 sub. sequently broken the switch is mounted on a pivoted base which may be rocked either by a handle 13, electromagnet 15 or by eccentric cam or other means. The switch may be returned after the resetting movement either by a spring or gravity and normally rests against a rubber stop 12. A small opening or channel may be provided at the inner end of the side limb by which the mercury trapped therein may flow slowly back into the main body of mercury even if the switch remains untilted after its operation.