GB480783A - Improvements in and relating to synchronised electric drives for printing presses and like machines - Google Patents

Abstract

480,783. Maintaining equal speeds of motors. BRITISH THOMSON-HOUSTON CO., Ltd., and CLARK, L. J. July 24, 1936, No. 20564. [Class 38 (iii)] The several units of a printing-press are driven by individual motors 1, and maintained in synchronism by alternating- current machines 2 interconnected on their primary and secondary sides, a master synchronizing machine 7 connected on the primary and secondary sides with the machines 2, being driven by an independent motor 8 for effecting slow speed operation. The connection of the secondary of the machine' 7 with the secondaries of the machines 2 is made by a contactor D closed under the control of a relay 14. This relay comprises a machine having a' stator winding connected the secondaries of the machine 2, and a rotor winding connected to the secondary of the machine 7. It operates a contact arm 16 to close the circuit of the contactor D when the voltage in the secondary of the machine 7 is in phase with that in the secondaries of the machines 2. When an " inch " button is operated a contactor I closes followed by the closing of contactors A, E, C, and J. The machine 7 is thus driven at slow speed by the motor 8, and when the relay 14 operates the contactors B and D close. Thus the units operate at creeping speed in synchronism, the motors 1, which are of the alternating- current commutator type, also being connected and assisting the drive. When the " inch " button is released, the contactors I, D. B, E, C, and J open followed after a time interval by the contactor A, the energization of the synchronizing machines being maintained until the units come to rest. For continuous running a " raise " button is operated to close a contactor R, and subsequently the contactors A, E, C, and J. When the relay 14 operates the contactors D and B close. The units again operate in synchronism at creeping speed under the control of the machine 7. The contactor B in closing also closes a contactor F which energizes pilot motors for operating the brush gear of the motor 1 to increase the speed. A limit switch 7, on the brush-gear of the motor 1 operating the folder unit, which motor will always form one unit of an effective grouping, opens when the brush-gear is operated, and releases the contactors D. E, C, and J. Thus the machine 7 and its driving motor 8 are disconnected, and the units are accelerated without restraint. Acceleration is stopped by releasing the '' raise button, a limit switch X on the brushgear of the motor 1 operating the folder unit having the same effect if the brushes reach the maximum speed position. A contactor G is energized to cause operation of the brush-gear in a speed decreasing direction by operation of a " lower " button. Upon operation of a " stop " button the contactor B opens and a contactor H closes. The contactor H in closing connects resistances 10 in the secondary circuits of the machines 2, and since the machines 2 normally operate in a direction opposed to the direction of their field rotations, the several units are braked. A time interval after the contactor H closes which interval is sufficient to enable the units to come to rest, the contactor A is opened. A switch W is operated when the folder unit comes to rest to deenergize the contactor H. Before interconnecting units which are to form a group, they are brought into correct relative angular relationship, and for this purpose isolating means are provided to establish connections for operating any individual unit in combination with the machine 7 and to isolate the other units. When the contactor A, which connects the primary windings of the machines 2 to the supply, is open, the machines 2 are excited at a reduced value through reactors 11, to avoid accidental relative movement of the units. Specifications 391.239, 391,246, and 429,837 are referred to.