Potter PFC-9000 Series User Manual
Page 43
43
PFC-9000 • 5403535 • REV G • 9/08
PSCI Short Circuit Isolater
When a short circuit or direct wire to wire short occurs on the SLC loop, the communication on the entire loop will be lost and the
panel will have numerous trouble conditions because of the missing devices. The PSCI is a short circuit isolator that will isolate a
short circuit to a portion of the SLC loop and keep a portion of the loop operational instead of losing the entire SLC. The PSCI is
self-restoring, therefore when the short is removed the device will automatically reset. The PSCI is not addressable. Therefore, it
does not require addressing.
Potter recommends that at a minimum, a PSCI is installed in Class A (Style 6) and Class B (Style 4) loops at the start of every
floor or wing, the start of every T-Tap, and at least one after every 20 devices. Class A (Style 7) installations require a PSCI close
nippled to each side of the smoke sensor or module.
The SLC loop has a maximum loop resistance of 50 ohms. As each device on the SLC loop reaches an alarm condition, the LED’s
will latch on and the loop will support a maximum of 15 LED’s in alarm. The LED on the device is particularly important for the
ADSD-PR because the LED’s latch the relays on the device.
Each PSCI added will reduce the total allowable resistance of the loop. As the LED’s on the loop are powered, the current of the
loop increases and thus reduces the amount of resistance. The following table indicates the number of PSCI’s that can be installed
on the loop and the maximum loop resistance.
s
r
o
t
a
l
o
s
I
f
o
r
e
b
m
u
N
s'
D
E
L
5
1
m
u
m
i
x
a
M
s
'
D
E
L
5
f
o
m
u
m
i
x
a
M
I
C
S
P
0
2
0
5
0
5
I
C
S
P
0
4
4
4
0
5
I
C
S
P
0
6
6
3
0
5
I
C
S
P
0
8
8
2
0
5
I
C
S
P
0
0
1
0
2
0
5
I
C
S
P
8
2
1
0
1
6
3
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω