CABLE HEATING SYSTEM Russian patent published in 2001 - IPC

FIELD: electrical engineering; heating rooms, roofs, etc; built-in heating systems. SUBSTANCE: system has non-shielded insulated wire 1 above conducting shield 3. Wire 1 is locked in position by means of concrete brace 4 relative to surface of heat shield. Ends of wire 1 are connected through connectors 5 and 6 to first end of wires 7 and 8; first end of wire 7 is connected to power mains neutral lead 9 which is connected to ground circuit 10. Novelty is that system has input protective device 11 incorporating current-failure relay 12 whose coil 13 has one of its leads connected to lead 8 and other one, to power mains phase lead 17 through circuit set up of series-connected normally open contact group 14 of control-circuit relay 15 and normally open contact group 16 of relay 12. Connected in parallel with contact group 16 of current-failure relay 12 is system on-button 18. Current induced in series control circuit causes operation of relay 15 with the result that control circuits and contacts of its normally open contact group 14 close. Current induced in coil circuit of current-failure relay 12 flows in wire 1 with the result that relay 12 operates and contacts of its normally open contact group 16 close to hold system in this position until control circuit is opened by pushing system off-button 21. Pushing this button de- energizes coil 20 of control-circuit relay 15. EFFECT: reduced strength of electromagnetic-field electrical component in system environment; improved safety of system. 12 dwg