Patent GB-470065-A (GB)
Title: Improvements in and relating to electric motor control equipments
IPC: B60L15/04
Filed: 1936-02-03
Abstract: 470,065. Master control of D.C. motors; controllers. GRAY, W. T., and METROPOLITAN - VICKERS ELECTRICAL CO., Ltd. Feb. 3, 1936, Nos. 3224 and 10541. [Class 38 (iii)] Armature and field control combination of resistances.-A sectionalized resistance which may be graded is first connected in series with the armature of a series-wound motor, and then partly or wholly in shunt with a part or the whole of the field winding, a servo-operated power drum controller, having contacts through which two sets of-intercalated tappings of the resistance are connected with respective lines constituted by connections between controller contacts, being provided, to effect a graduated sequence of tap-stepping and interconnection of tappings both when the resistance is in the armature circuit and across the field, thereby to vary progressively and without retrogression the value of the resistance by a series of multiple path connections from a value corresponding to one, or a comparatively small number of paths, to a value involved by a multiple connection to a plurality of tappings, switching means additional to the power controller being provided together with interlocking means for operating the additional switching means to break main current circuits before the said circuits are broken at the power controller. The invention is described as applied to a series-parallel control system for two motors M1, M2, controlled by a power controller comprising two mechanically coupled portions 109, 110, and having operative positions 1-45, the controller being actuated by means as described in Specification 451,514 under the control of a master controller. Upon operation of a reverser drum 132, reversing switches 101, 102, are operated, and line switches LSI, LS4, closed over interlock contacts 159. With the master controller 131 actuated to an operative position, a switch JR is energized over interlock contacts 162, 163, on the line switch LS3 and a switch J, and the motors M1, M2, are connected in series with each other and with resistances RR1-RR5 and R2-R5. A coil 170 is energized in the first position of the drum switch over controller interlock contacts 125 and air pressure is applied to the servomotor. Coils 168 and 169 of the " off " and relief valves are energized when the controller 131 is actuated, and a feed coil 178 is also energized so that the power controller is moved under the control of a current limit switch 179. If the controller 131 is in its second position, the power controller moves until a finger 180 controlling interlock contacts 126 is disconnected. In this position, the power controller gives full series operation. During this movement of the power controller the resistances R1-R5, and RR1-RR5 are gradually removed as described in Specification 469,958, The connections between the resistance tappings and the controller fingers are divided into two groups, crossing each other so that crossing of conductors between drum segments is avoided, the segments of the drum may be built up in units, each comprising all segments connected together and the units being fitted from opposite sides of the drum. The coil OCJ of the switch J is energized in the full series position over interlock contacts 125, and the power controller circuits may be broken without arcing. By further movement of the controller 131 the power controller is operated to give full parallel connections and two weak field positions, the interlock contacts 125 controlling the line switches LS2, LS4. The removal of the resistances in each of these further stages is also effected as described in Specification 469,958, and the movement of the controller is regulated by the current limit relay 179. The connection of the accelerating resistances across the respective fields is made through low resistances RR6, and R6, respectively whereby the values of the two shunt circuits are adjusted. Movement of the power controller may be stopped at any stage by returning the controller 131, whereby the interlock contacts 126 disconnect the feed coil 168. Upon returning the controller 131 to the off position the line switches are opened, and the coils 168, 169, 170, of the servomotor are de-energized, and the power controller returned to its off position. The application of power to the motors is prevented until the power controller reaches the off position to reclose interlock contacts 159. The line switches are also opened when overload relays 161 open and to reset the overload trip by operating a push button 135, the controller 131 and the power controller must be in their " off " positions, to reclose contacts 147 and 198. Similar control is effected when no-volt relays 177 operate. When the power controller reaches the full parallel and second weak field positions, the interlock contacts 126 close the circuit of a signalling device, the circuits of several equipments operating in multiple unit being connected in series so that the signal is given when all equipments reach the full parallel or second field positions. The circuits from the controller 131 to the interlock contacts 126 include the contacts of respective relays 184, 185, 186 energized from the controller 131, so that for multiple unit control, any difference in time taken by the several power controllers to reach the positions determined by the controller 131, will not result in feed back between adjacent train line wires at interlock contacts 126. The line switches may be opened by actuation of a test push button 134, and the controller 131 moved to the fifth position, the power controller moving rapidly to its final position. If the signalling means do not operate test plugs 195 of the several equipments may be operated in turn and the faulty equipment detected. The power controller may be provided with additional switches comprising a fixed contact and a co-operating movable contact electrically and mechanically connected with a moving drum switch having a cam engagement with the movable contact member whereby the latter is actuated into engagement with the fixed contact after engagement of the drum contact.