Loop
Loop
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
First isolator
with detector
Last isolator
with detector
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
Α’
topology
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
Α’
topology
Short Circuit
ON
OFF
OFF
ON
Address
Detector ON
Address
Detector ON
Address
Detector ON
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
A
P
1
2
3
4
5
6
7
8
ON
Β’
topology
OFF
OFF
OFF
OFF
OFF
Address
Detector ON
Β’
topology
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
-R
O
U
T
-
-
N
L
I
+
U
T
R
O
+
L
IN
+L -L +L -L
A
P
1
2
3
4
5
6
7
8
ON
C
’
topology
Short Circuit on Loop Wiring
Simple detectors
Isolator
Isolator
Simple detector
Isolator
with detector
Isolator
with detector
+L
+L
+L
+L
+L
+L
+L
+L
+L
+L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
+L -L +L -L
Page 2 from 5
Electrically, the attached detectors are connected to the output of each isolator. This is why
regardless the isolator state it is possible the attached detectors to be operational, like the
above two topologies
(Α
and
Β).
Simple detectors
Call point
921707100_09_00
6
