Patent GB-1318085-A (GB)
Title: Apparatus for detecting faults in elongated flexible material
IPC: G01R31/02
Filed: 1970-04-27
Abstract: 1318085 Automatic speed control BRITISH INSULATED CALLENDERS CABLES Ltd 27 April 1971 [27 April 1970] 20025/70 Heading G3R [Also in Division G1] Apparatus for automatically decelerating and reversing movement of a running elongate flexible material e.g. insulated wire, on detection of a fault by at least one detector 18 comprises reversible drive means for the material W and a device for integrating the velocity of the material, the arrangement being such that a signal generated by the fault detector 18 upon a faulty region of material passing it, energizes the integrating device and causes the reversible drive means to decelerate and eventually reverse the direction of movement of the material until the integrated value of the velocity is approximately zero i.e. the faulty region of the material is brought back to a position adjacent to the detector. The velocity in the reverse direction is taken as  being negative for the purposes of integration. The material W is fed from a reversible feed drum 16, past at least one fault detector 18 to a reversible take-up drum 1. The take-up drum 1 is preferably driven by a reversible electrical motor 20, the field windings 21, 22 of which are fed by a DC amplifier 23. The motor 20 also drives a tachogenerator 11 connected across a potentiometer 8. The adjusting arm 9 of the potentiometer is controlled by a lever 4 detecting the radius of the coil on the take-up drum 1. The voltage Vo, a measure of the velocity of the material, is fed to the amplifier 23 together with the output of a ramp function generator 27. The output voltage Vo is also fed upon detection of a fault to a computing amplifier and a device which squares the voltage Vo. The output of the computing amplifier is fed via a scaling amplifier to a zero voltage detector. The squared voltage (Vo)<SP>2</SP> is fed together with a signal from the scaling amplifier to a comparator, the output of which is fed to a second zero voltage detector. The comparator can be adjusted to provide a signal for controlling the ramp function generator to bring out the required deceleration to stop the motor 20 shortly before the output from the computing amplifier reaches nearly zero. The ramp function generator is designed to inch the motor 20 until the first zero voltage detector emits a signal to switch the ramp function generator and to brake the take-up drum. The first zero voltage detector is arranged such that is does not operate until it receives a signal from the second zero voltage detector. The output from the first zero voltage detector is also arranged to activate a visual or audible warning signal to indicate the material is ready for repair, which signal persists until the fault is repaired. At each end of the reciprocal movement of the traversing member for the take-up drum, there are two stop and two micro-switches which are staggered in the direction of movement of the member in such a way that, if reversal of the reversible drive for the material takes place immediately after reversal of the said member as been effected by one micro-switch, the continued movement of the member that would otherwise take place is reversed by actuation of the second micro-switch. Safety switches to stop the reversible drive means in the case of malfunction of the traversing member are also provided.