Theory Of GEB : -
A flameproof
enclosure primarily for use at or near the coalface and designed to line up
with similar boxes to form a control board. A gate-end box may contain bus
bars, isolators, switches, contactors, transformers, and protective devices,
for the control of motors, lighting, and other equipment.
The
gate end box is always placed in the fresh air, so that there is no danger of
gas on coal dust explosion due to spark. The gate end box is used to supply the
power to the CCM trough a five core cable (three power core, one pilot core
& one earth in core). The main switch of the CCM which works on 550 volts
is placed at the gate end box & it is operated by switch which is located
at 30 volts, hence CCM is known as “Remote Control Machine”
Advantages
of Gate End Box:-
1) Closing
& opening of coal cutting machine (CCM) motor is done away from the face
which is well ventilated & safe.
2) If
the pilot conductors are opening circuited the main conductor automatically
trips.
3) If
the trailing cable is damaged causing short circuit, the main conductor
automatically trips.
4) If
the supply fails or flexible cable is removed or the plug are not fully
inserted then again main conductor trips.
5) After
the insertion of power the coal cutting machine (CCM) motor can’t be started
until the starter handle is put back to off position & then to on position.
6) Control
on the coal cutting machine (CCM) is simple & easy to operate.
7) Power core
is flexible cable is allow only when the coal cutting machine (CCM) is running
Components Of Gate End Box:-
1) The upper chamber
a) Bus Bar
b) Isolator
2) The lower chamber
a) Air circuit breaker
b) Core balance transformer
c) Earth fault relay
d) 3 numbers of plunger type oil dash pot overload relay
e) Interlock coil
f) Auxiliary
CIRCUIT DIAGRAM LATEST GEB :
Three mode of operation
1) OFF MODE
2) START MODE
3 RUN MODE
