Abstract: A railroad track circuit providing for the positive detection of broken rails despite the presence of factors that would otherwise preclude such detection is disclosed. These factors include sneak paths arising from the presence of negative return cross-bonding as applied between parallel tracks in electrified territory. Broken rail detection is ensured through the provision of two track relays, or devices that function as track relays, uniquely arranged so as to render the track circuit immune from these factors.

Abstract: A railroad track circuit providing for the positive detection of broken rails despite the presence of factors that would otherwise preclude such detection is disclosed. These factors include sneak paths arising from the presence of negative return cross-bonding as applied between parallel tracks in electrified territory. Broken rail detection is ensured through the provision of two track relays, or devices that function as track relays, uniquely arranged so as to render the track circuit immune from these factors.

Abstract: A method and apparatus detect completely broken rails in an unoccupied section of railroad track including two rails without insulated joints by subdividing the track section into current loops and applying commercial AC power near the physical center of the track section while causing, under the condition of the rails being intact, approximately equal currents to flow in each resulting half of the track section. Currents are sensed through induction of voltages in an electrically-isolated coil mounted directly to the rails. A rail break is detected from a subsequent decrease in the coil voltage resulting from a reduction of current due to the rail break in at least one half of the track section with respect to a reference value determined while the rails were intact and due to the break.

Abstract: A method and apparatus detect completely broken rails in an unoccupied section of railroad track including two rails without insulated joints by subdividing the track section into current loops and applying commercial AC power near the physical center of the track section while causing, under the condition of the rails being intact, approximately equal currents to flow in each resulting half of the track section. Currents are sensed through induction of voltages in an electrically-isolated coil mounted directly to the rails. A rail break is detected from a subsequent decrease in the coil voltage resulting from a reduction of current due to the rail break in at least one half of the track section with respect to a reference value determined while the rails were intact and due to the break.