An electrical system whereby a circuit is monitored to prevent application
or restoration of supply if an earth fault exists. BS, 13
An instrument for measuring the insulation fault at low voltage without
polarization. This instrument is more informative in checking detonators
in loaded holes than the insulation meter. Langefors
A system of protection designed to cause the supply to a circuit or system
to be interrupted when the leakage current to earth exceeds a
predetermined value. Also called earth leakage protection. BS, 13
An apparatus used to prevent or reduce current leakage to the ground when
blasting in conducting orebodies, in wet shale or clay, and in underwater
blasting, esp. in salt water. The apparatus has no battery and can be used
when loading the hole to check if the conducting wires have become damaged
during this operation. Syn:current leakage tester
An early name for fine silky asbestos. See also:amianthus
A mass-movement landform and process characterized by downslope
translation of soil and weathered rock over a discrete basal shear surface
(landslide) within well-defined lateral boundaries. Little or no rotation
of the slide mass occurs during displacement. Earthflows grade into
mudflows with increasing fluidity. Also spelled: earth flow. AGI
A soft or earthy variety of calcite. See:aphrite
Establishing an electrical connection between a conductor and the earth.
An important safeguard in electrical installations. Nelson
An electrical system in which all the conductors are earthed.
Nelson
A protective system that operates as a result of leakage of current from
electrical machines to earth. For electrical apparatus in mines, the usual
method of leaking protection is known as the core balance system. This
depends for its action on the balance of the currents in three phases.
When a fault occurs, the balance is disturbed and the resulting magnetic
effect in the transformer core induces a current in the secondary circuit,
so energizing the tripping coil and operating the tripping mechanism on
the circuit breaker. It may be operated by a leakage current as low as 5%
of the full load current of the circuit. Nelson
See:hoodoo; pillar.
a. A local trembling, shaking, undulating, or sudden shock of the surface
of the earth, sometimes accompanied by fissuring or by permanent change of
level. Earthquakes are most common in volcanic regions, but often occur
elsewhere. Syn:temblor
b. Groups of elastic waves propagating in the earth, setup by a transient
disturbance of the elastic equilibrium of a portion of the earth.
AGI
See:crust
See:shell
Downslope movement of part of an earth embankment sufficient to break up
blocks and pulverize the material so that it moves in a somewhat fluid
manner. CF:earth slump
The angle of superficial slope naturally assumed by rock debris, earthy
detritus, etc., when piled up in mounds or ridges. Standard, 2
Downslope movement of part of an earth embankment in blocklike masses
without other apparent deformation. CF:earth slide
A term that may be applied to mined amber to distinguish it from sea
amber. CF:earth amber
An obsolete syn. of seismic wave. AGI
See:ozocerite
a. Consisting of minute particles loosely aggregated; claylike, dull.
b. In mineralogy, roughish to the touch, dull and lusterless. Porous
aggregates of a mineral, such as the clays, scatter incident light so
completely that they seem to be without luster and are described as dull
or earthy.
c. Composed of or resembling earth or soil; e.g., an "earthy limestone"
containing argillaceous material and characterized by high porosity,
loosely aggregated particles, and close association with chalk.
d. Said of a type of fracture similar to that of a hard clay.