S
S
I
I
L
L
B
B
U
U
S
S
R
R
E
E
P
P
E
E
A
A
T
T
E
E
R
R
5
5
O
O
F
F
1
1
0
0
120-321-12
T
T
Y
Y
P
P
E
E
SILBUS-A2WCCT2
U
U
S
S
E
E
R
R
'
'
S
S
M
M
A
A
N
N
U
U
A
A
L
L
I
I
s
s
s
s
u
u
e
e
:
:
0
0
1
1
3 TYPICAL APPLICATIONS
3.1 CONVEYOR THAT PASSES FROM A HAZARDOUS AREA TO THE SAFE AREA
Many underground coal mines have at least one conveyor belt that transitions from a
hazardous area to the safe area, this conveyor is typically known as the drift belt and it
brings coal from underground to the surface and up to the coal washing plant or stacker-
reclaimer. About three quarters of the drift belt is underground and in the hazardous area
while one quarter is above ground and in the safe area. The repeater can simplify the
SILBUS belt monitoring and control system installation by splitting the system into non-
intrinsically safe and intrinsically safe sections at the transition point, typically just inside
the mine portal. The repeater eliminates the need for signal draining zener barriers at the
transition point.
BOX CUT
DRIFT BELT
PORTAL
HAZARDOUS AREA
SAFE AREA
- INTRINSICALLY SAFE PULL SWITCH
- REPEATER TYPE A2WCCT2 AT TRANSITION POINT
- NON INTRINSICALLY SAFE PULL SWITCH
- NON INTRINSICALLY SAFE SILBUS NETWORK (PRIMARY)
- INTRINSICALLY SAFE SILBUS NETWORK (SECONDARY)
- CHANNEL GENERATOR
DRIFT
(REQUIRES INTRINSICALLY SAFE 12V POWER SUPPLY)
SURFACE
Figure 1 Typical drift belt installation
3.2 PROVIDING GALVANIC ISOLATION WITH LIGHTNING PROTECTION
The repeater type SILBUS-A2WCCT2 has inherent segregation and galvanic isolation
between the primary network port and the secondary network port that is useful in filtering
the effects of lightning induced surges that may be present on a primary non-intrinsically
safe SILBUS network.
HAZARDOUS AREA
SAFE AREA
SEPARATE
FUNCTIONAL
REPEATER
TYPE
A2WCCT2
INHERENT SEGREGATION AND
GALVANIC ISOLATION OF REPEATER
EARTH
SEPARATE
FUNCTIONAL
EARTH
PRIMARY
LIGHTNING
PROTECTION
PROTECTION
LIGHTNING
SECONDARY
PROTECTED
INTRINSICALLY
SAFE SILBUS
NETWORK
NETWORK
SAFE SILBUS
NON-INTRINSICALLY
DO NOT CONNECT EARTHS
Figure 2 Galvanic isolation with lightning protection
