GB190411168A - Improvements in Safety Devices for Protecting Dynamo Electric Machinery and the like against the Excessive Voltage occuring when they are Switched In or Out. - Google Patents

Abstract

11,168. Elektrizitõts Akt.-Ges. vorm. W. Lahmeyer & Co. June 27, A.D. 1903, [date applied for under Patents Act, A.D. 1901]. Armatures ; field magnets.-In order to protect the windings of motors, transformers, and the like from the abnormallyhigh voltages occurring when they are switched in or out, a choking-coil is interposed between the winding and the mains, and is short-circuited or otherwise rendered inoperative during normal working conditions by means controlled by the main switch. A form of switch for putting the coil successively in and out of action is shown in Fig. 5. A pin F, permanently connected with one of the leads, is capable of being moved by a lever into contact with a sleeve H joined to the choking-coil D which protects the winding W, the choking-coil being shortcircuited when the pin reaches the contact U. Alternatively, the self-induction of the choking- coil may be reduced by short-circuiting a second coil in inductive relation to the first, or, as shown in Fig. 7, the core K of the coil D may be withdrawn after closing the main switch S. The core may be in the form of a horse-shoe, and the magnetic resistance is increased by removing its armature in a similar manner to the above, or the core may be furnished with an auxiliary winding fed from a source of direct current, such as a battery, so that, after completing the main circuit, a second switch, mechanically coupled with the main switch, closes the battery &c. circuit, thus saturating the iron core. A single choking-coil may be used in connection with several machines.