Earth tremor or subsidence mine gallery warning system - employs pairs of geophone probes connected by line to control unit

摘要

A mine warning system to give protection against earth tremors, subsidence etc., has a series of geophonic probes (G1-G4) positioned in e.g. the upper gallery (100) and lower gallery (102), and connected by cables through connecting galleries (101) and to a switching unit. This is connected to a limiting valve switch and a coincidence circuit and timing system for each pair of probes in a circuit which operates an alarm. Horizontal and vertical gephones can be used. The appts. includes a unit with a power supply section, the limiter switch section and the connection unit. The limiter switch section has a door with a lock for access for testing, adjustment, repair etc. and a window for the optical indicator. It also has a voltage selector and a selector switch.