DEVICE TO PROTECT LIFTING CRANE FROM DANGEROUS VOLTAGE IN TRANSMISSION LINE Russian patent published in 1998 - IPC

FIELD: lifting crane safety system. SUBSTANCE: device has electric field indication unit 1 with sensitive element 2 and amplifier 3, signalling unit 9 with comparison and threshold changeover unit 17, switching unit 19 and communication line 6. Result is obtained owing to introduction of voltage-to-frequency converter 4 into electric field indication unit 1 and separator-pulse shaper 16 into signalling unit 6. EFFECT: improved interference protection of communication line without laying additional cable to crane and possibility of bringing the crane out of dangerous zone when protection operates at inadmissible approaching of crane to high voltage lines. 4 cl, 1 dwg