GB613441A - Improvements in or relating to mercury arc rectifiers and like mercury cathode devices - Google Patents

Abstract

613,441. Rectifying. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Jan. 7, 1946, No. 621. Convention date, Nov. 4, 1944. [Class 38 (ii)] [Also in Group XL (a)] For the purpose of anchoring the cathode spot, the exciting electrode of a mercury vapour rectifier consists of an auxiliary anode 11, in the form of a rod and a second anode 10 in the form of a tube enclosing the anode 11 and provided at its end with a constricted aperture 131 flaring towards the cathode 14. The anodes may be formed of iron tipped with refractory metal, such as tungsten, 12, 13. The starting may be effected by moving the anodes into and out of contact with the mercury pool ; preferably, a high resistance spark-plug 20 is used. As applied to a three-phase supply rectifier, the power anodes 6 ... 9 &c. are disposed in a circle, each in a cylinder 19 ; the exciting electrodes are surrounded by a cylinder 18 forming a condensing chamber; the cathode container is a metal cup 2 bolted through an insulating washer 3 to the metal envelope 1; and a ring 15 of insulating material such as quartz or the material known under the Registered Trade Mark " Pyrex " confines the mercury pool. In operation, voltage is applied to the exciting electrodes from one of the supply phases from the transformer 32 through a rectifier 36, and resistance 38 to reduce the voltage of the electrode 10 relatively to 11. Simultaneously, a high voltage is applied to the starting electrode 21 by a transformer 23 through the contacts 41. When the exciting arc shorts, the contact 41 is broken by the relay coil, and the circuit of the coil 39 of a circuit-breaker closed through the contact 40. This applies the three-phase voltage to the power anodes through the transformers 28, 29, 30. The rectified current appears at the lines 43, 44.