Stop-motion apparatus of weaving looms

In stop-motion apparatus of a weaving loom of the type wherein the output from an abnormal signal generator is applied to a counting circuit, said generator generating the abnormal signal when it detects an improper insertion of a weft yarn, said counting circuit is reset by a reset pulse generated by a reset circuit when the weaving operation of a unit length is completed, said counting circuit produces an output when the number of the abnormal signals applied to the counting circuit exceeds a predetermined limit while said unit length is being woven, and said output is utilized to open the circuit of the driving means of said weaving loom, the improvement which comprises a second counting circuit connected in parallel with said first mentioned counting circuit, means to apply the output from said abnormal signal generator to said second counting circuit, a second reset circuit which generates a second pulse each time a reference length of the fabric equal to a multiple of said unit length is woven, means to apply said second pulse to said second counting circuit for periodically resetting the same, means for causing said second counting circuit to produce an output when the number of the abnormal signals applied to said second counting circuit from said abnormal signal generator exceeds a second predetermined number during an interval between said second pulses, and means responsive to the output from said second counting circuit for opening said circuit of the loom driving means.