GB128338A - Improvements in or relating to Automatic Delayed Action Electric Switches. - Google Patents

Abstract

128,338. Woodhouse, A. E. May 4, 1918. Controllers w i t h auxiliary switches; with mercury contacts.-An automatic delayedaction switch comprises a mercury container b communicating by an adjustable orifice e' with a chamber c containing a float valve m so that, when the switch member is swung through 180 degrees about the contact pivot g into the position shown (where a contact located at the upper end of the switch member and connected with the interior contact j engages with a fixed contact h), the mercury parses into the float chamber, and, after a certain time, raises the float which opens the adjustable orifice f<1> letting the mercury into the terminal chamber d where, after a further time depending on the height of the terminal j, the external circuit is completed. The switch may be used in association with a variable resistance as a motor starter. In the form shown in Fig. 3, the switch member is extended below the terminal chamber to constitute two chambers 5, 6 separated by a partition with an orifice 4. The upper chamber contains resistance material such as carbon granules which, when the switch is set in the position shown to start the motor, gradually fall into the lower chamber and fill up the annular space between the sleeve 7 connected by spring blades 3 to the external contact 2 and the metal casing a similarly connected to the other external contact. The resistance in the motor circuit is thereby gradually lowered and at the same time the mercury is flowing into the float chamber. The float is so set that when the resistance has been sufficiently reduced the float lifts and the mercury connects together the contact 1 and the outer casing, thereby short circuiting the resistance. The combined switch and resistance member is pivoted between its ends and, when swung round to the unset position, the fixed contacts are not engaged.