GB644058A - Improvements in or relating to remote control devices for electric apparatus - Google Patents

Abstract

644,058. Protective cut-out arrangements. MINES DOMANIALES DE POTASSE D'ALSACE. Aug. 7, 1947, No. 21654. Convention date, Jan. 3, 1946. [Class 38(v)] A remote-control arrangement for A.C. apparatus, for use for example in mines, comprises a pilot circuit normally carrying a rectified current and formed by an insulated conducting sheath G for the connecting cable and an earth return, comprising a conductor in the cable, or the earth itself. The contactor 2 is closed by moving contact 19 to position a, so that relay coil 14 is energized by a current rectified by 16, so as to close the circuit of coil 5. The contact 19 is then moved to position b and the relay 14 is energized by a reduced current. The contactor 2 is manually opened by moving contact 19 to position c and automatically opened upon voltage failure. It is also opened upon the sheath G becoming earthed, since in this event the rectifier 16 is short-circuited, and the coil 14 is short-circuited by a shunt condenser 15, the pilot circuit itself being opened by a relay 22 fed by a rectifier 21 reversely connected to rectifier 16 and passing the alternations normally stopped by the latter. A visible indicator, such as a lamp or electromagnetic vane or needle, may be inserted in the conductor feeding the condenser 15. The cable may comprise three main conductors and an earth return conductor, with an insulated conducting sheath G, (Fig. 3 not shown).