GB1270544A - Improved fluidic control system - Google Patents

Abstract

1,270,544. High voltage switches. ALLISCHALMERS MFG CO. 28 Nov., 1969 [3 Dec., Dec., 1968], No. 58364/69. Heading H1N. [Also in Division F1] A fluid logic switching circuit for providing pulses alternately to actuating cylinders If, le e.g. the close and trip cylinders of a gas blast circuit breaker having poles la, 1b, 1c each provided with an isolating chamber and pole switches (not shown) comprises (1) a first pushbutton 6 connecting a low pressure supply line 5 with a preferential flip-flop 7 and an OR-NOR gate 8 thereby providing a pulse which opens a valve 12 in a high pressure gas line from a supply 1d to cylinder 1f until such time as pressure in a capacitor 10 vents the output of the flip-flop with consequential switching of gate 8 to the NOR leg (2) a second push-button 13 which connects the low pressure line 5 with a preferential flip-flop 14 and an OR-NOR gate 15 which provides a pulse transmitted through a passive OR gate 19 to open a valve 20 in a high pressure line leading to cylinder 1e until such time as pressure in a capacitor 17 moves flip-flop 14 to the vent position with consequential switching of gate 15 to the NOR leg (3) normally open switches 11, 18 in the preferenced outputs of flip-flops 7, 14 respectively and responsive to high pressure supply and preventing generation of either pulse when pressure in line 5 is below a predetermined level (4) means for sensing the position of the pole switches for controlling a feed back logic system and thereby providing a pulse to open valve 20 thereby tripping the breaker 1. Assuming breaker 1 and all pole switches open these with all isolator chambers pressurized, pressure in lines 21a, 21b, 21c open check valves 22 and a valve 25 in line 5 thereby connecting the low pressure supply to OR-NOR gates 26-31. Since pressure in lines 21a, 21b, 21c also opens valves 32 to 34 pressure in line 5 is transmitted to the control inputs of gates 26, 27, 28 to switch their outputs to their OR legs. There being no NOR outputs at gates 26 to 28 which are connected to the control inputs of gate 30, the NOR output of gate 30 causes the gate 31 to have an OR output which is vented. Similarly with breaker 1 and all pole switches closed, lines 21a, 216, 21c are depressurized, valves 32 to 34 close and the outputs of gates 26 to 28 return to their NOR legs resulting in there being no input to gate 29 so that the NOR output thereof which is fed to the control input of gate 31 switches the output of the latter to its OR leg i.e. vent. In the event of a malfunction wherein at least one pole switch is open and at least one closed then pressure in one or two of lines 21a, 21b, 21c opens valve 25 to provide supply pressure to gates 26 to 31. At least one switch 33 to 34 will be open and at least one closed whereby at least one gate 26 to 28 will have an OR output and at least one will have a NOR output. Both gates 29, 30 will have OR outputs and gate 31 will have a NOR output which is transmitted through a resistor 35 to the passive OR gate 19 resulting in opening of valve 20 and operation of the trip cylinder le.