Patent GB-190623894-A (GB)
Title: Improvements in and relating to Electric Motor Control Systems and Apparatus.
Filed: 1906-10-26
Granted: 1907-12-24
Abstract: 23,894. British Thomson-Houston Co., [General Electric Co.]. Oct. 26. Switches.-Relates to systems for controlling motors from a distance by push-switches, for example motors used for driving printing-machines. The chief feature of . the invention consists in an electromagnetically-operated master switch for governing the operation of a controller of the separately-actuated . electromagnetic-contact type, said master switch being controlled so as to move step by step towards or from the off-position, or to move continuously towards the off-position. Banks of push-switches are provided, each containing an accelerating, a retarding, a stop, and a safety push. To accelerate the motor, the racked stem k<5>, Figs. 1 and 3, of the master switch, is raised step by step by a pawl d<1> which is pivoted to the core of a solenoid D, the pawl being pivoted also to a swinging arm d<2>. Each time the core is raised, the pawl lifts the racked stem k<5> sufficiently to cause the contact k<4> to travel one step on to the next contact. Current is supplied to the solenoid D from the main l through conductor 1, and passes through a bridgeswitch d<3> and wire 2 to a closed "accelerating" push-switch G in one of the banks, e.g. the left one, across contacts g, to wire 3. The circuit of the solenoid D is broken by its own core at the bridge d<3> when the core is drawn right up, and the latter then drops with its pawl, allowing the circuit to close again. This gives an intermittent lifting action to the pawl d'. After each stroke, the rack is latched by a pawl f<1>, which has one of its arms 40 pressed by a spring 42 against one side of a slot 41 in the core of the latching-solenoid F. The latter is energized from the wire 1, current passing through the wire 8 through the cable to contacts g' of the switch G, where it meets the current from the solenoid D. From here current passes to the next bank through the wire 3, branch 3<a>, safety switch J, wire 4 to the first bank, safety switch J of the first bank-wire 5, stop-switch I, wire 6, to the second bank stop switch I, wire 7 through cable to relay throttle O, and then to the other main. After the master-controller stem has been in this way sufficiently raised, the current, after leaving the solenoid F, passes, instead of by wire 8, through the wire 9, segment k<3>, and contact k<4> to segment k<2>, through wires 10 and 5<a>, the latter being connected through the cable to the point 5<b> on the wire 5. From here the current from the latching-solenoid F passes through the safety and stop switches as before, and is independent of the accelerating-switch G. The accelerating- current, besides depending for its existence on closure of the push-switch G, passes also through the safety and stop switches of both banks, the stop switches being normally closed, and the safety switches free but held closed to enable the accelerating current to pass. When the master-switch stem is completely raised, it lifts an elbow d<4>, which in turn raises the bridge d<3> and holds it permanently off the contacts, deenergizing the solenoid, and also allowing the stem to be afterwards released when the current to the latching-solenoid F is broken at switches I or J. A third pawl el is employed, co-operating with the pawl f<1>, each of these pawls engaging the stem k<5> alternately so as to permit it to fall step by step. The pawl is operated by a solenoid E, which is energized by pushing the switch H, current passing from wire 1 to the solenoid, and then through the bridge e<2>, wire 11, and through the cable to wire 11 of the switch H, where it is bridged to the wire 5 and passes only through the stop-switches I in both banks. The core of the solenoid E has a pin 52, which takes loosely in between jaws on a bell-crank 46 pivoted to a fixed point 47. A shoulder 45 on the part 46 contacts with an extension of the pawl e<1>, and. holds the latter away from the rack when the solenoid is de-energized, the pawl being otherwise independent of the bell-crank but pivoted on the same pin 47. The upstanding arm of the crank has links 48 pivoted to it at one end, and at the other is formed with open jaws 49, into which a pin 50 on a pawl f is passed. The pawls e<1>, f<1> are connected together by a coiled spring 43, the whole arrangement being such that when the solenoid E raises its core, the pawl f<1> is pushed out of engagement with the teeth on the right side of the stem, and the pawl e<1> is pulled by the spring 43 into engagement with the teeth on the other side. As soon as contact is broken at e<2> by the core rising to its highest point, the pawl f<1> is caused to engage the stem, and so on. The stem is lowered by steps so long as the solenoid E is energized by closing the switch H. To lower the stem continuously to the ' off' position, the latching-solenoid F and the solenoid E are deenergized, when the pawls are drawn out of operation. The master-switch and separatelyactuated controller are described as governing a compound-wound motor. The armature M and series field M' are shunted across a variable resistance R in starting, the series field being cut out by a solenoid 32 after the resistance has been cut out. The shunt field 18 is weakened when the contacts k<4> travel over the contacts k<1> on the left side of the master switch.