Apparatus for detection of synchronism by means of vector difference measurement

Abstract From the Canadian patent

Solid state apparatus for the detection of synchronism between line and bus voltages in order to permit safer interconnection therebetween is disclosed. A first comparator circuit constantly monitors the magnitude of the vector difference between the line voltage and the bus voltage and generates a first enabling signal whenever the magnitude of the vector difference voltage is below a predetermined value. The first enabling signal will continue to be generated until the magnitude of the vector difference voltage rises above the predetermined value. A second comparator circuit monitors the relative magnitudes of the line and bus voltages and generates a second enabling signal whenever a …