Austdac TYPE SILBUS-A2WCCT2 User Manual - Page 5

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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.

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.
NON-INTRINSICALLY
SAFE SILBUS
NETWORK
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
T
T
Y
Y
P
P
E
E SILBUS-A2WCCT2
U
U
S
S
SAFE AREA
DRIFT BELT
BOX CUT
- CHANNEL GENERATOR
- NON INTRINSICALLY SAFE SILBUS NETWORK (PRIMARY)
- NON INTRINSICALLY SAFE PULL SWITCH

Figure 1 Typical drift belt installation

SAFE AREA
PRIMARY
LIGHTNING
PROTECTION
INHERENT SEGREGATION AND
GALVANIC ISOLATION OF REPEATER
SEPARATE
FUNCTIONAL
EARTH
DO NOT CONNECT EARTHS

Figure 2 Galvanic isolation with lightning protection

E
E
R
R
'
'
S
S
M
M
A
A
N
N
U
U
A
A
L
L
- REPEATER TYPE A2WCCT2 AT TRANSITION POINT
(REQUIRES INTRINSICALLY SAFE 12V POWER SUPPLY)
PORTAL
DRIFT
- INTRINSICALLY SAFE SILBUS NETWORK (SECONDARY)
HAZARDOUS AREA
REPEATER
SECONDARY
TYPE
LIGHTNING
A2WCCT2
PROTECTION
FUNCTIONAL
5
5
O
O
F
F
1
1
0
0
SURFACE
- INTRINSICALLY SAFE PULL SWITCH
HAZARDOUS AREA
PROTECTED
INTRINSICALLY
SAFE SILBUS
NETWORK
SEPARATE
EARTH
120-321-12
I
I
s
s
s
s
u
u
e
e
:
:
0
0
1
1