I
TYPE 4208 “W”
MC CULLOH LOOP MODULE
INTRODUCTION
The “W” module is used in the alarm-initiating
device circuit(s) of the “A”, “B” or “AX” panels
and it allows the alarm-initiating devices to operate
if there is an open in the circuit wiring. One “W”
module is required per zone.
CIRCUIT OPERATION (FIG. 27)
An open in the supervised alarm circuit wiring
causes a “trouble” signal (-24VDC) to be sent from
terminal 6 in the “A” or “AX” panel to relay K4
in the “W” module. (Refer to “A” or “AX” panel
- Trouble Condition for detailed circuit opera-
tion.)
When -24VDC is applied to relay K4, it energizes
and its contacts transfer.
When contacts K4A and K4B transfer, they pro-
vide an alternate alarm path for the alarm initiating
devices(s). For example, if alarm initiating contacts
circuit at point “X” current would flow from ter-
minal 4, through contacts K4A (5&g), terminal 3,
alarm initiating contacts “A” to terminal 1.
Contacts K4D provide a holding circuit for relay
K4. Current flows from terminal -24, through con-
tacts K4D (8& 12), relay K4 and diode D2 to ter-
minal +24. Also, -24VDC is applied out terminal 6
of the “W” module to terminal 6 of the associated
zone module. This keeps the zone TROUBLE lamp
illuminated and maintains a common trouble con-
dition (even though contacts K4A and K4B com-
“A” were closed while there was a break in the “A” were closed while there was a break in the
plete the circuit between terminals 4 and 1). plete the circuit between terminals 4 and 1).
I
6 6
w -24VDC
?
-T+
-24VDC
IN AT TROUBLE IN AT TROUBLE
4 4
-24
1
2
;
4
0
+24
p
Figure 27
48
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