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Document No: LT0122 F3200 Installation & Programming Manual
Installation & Wiring
Issue 2.7 5 July 2001 Page 8-21
8.6.1 DUAL POLE – POLARITY REVERSAL OUTPUT
Two relays; or 1 relay, an open collector output and an external 2 pole relay (e.g. PA0730);
can be arranged to provide a supervised dual-polarity output suitable for driving dual strobes
(Alert and Evacuate) or some visual warning devices (e.g. an AVI). The output is normally
off (supervising voltage only), but can turn on with 24V in one polarity or in the other polarity.
This is shown in Figure 8.6.2.
If the dual pole relay is a second 8RM relay then the additional connector blocks need to be
fitted (CN0260 and CN0488). Supervision is not enabled on this relay. The supervision on
the other relay will detect any short circuit, but may not detect an open circuit with multiple
sets of strobes/AVIs. This will depend on the type of strobe/AVI and the quantity remaining
connected.
The relay should be programmed to operate when either strobe is required, and the open
collector output (or 2
nd
relay) is programmed to operate for Evacuate.
Note that many strobes have a large capacitor inside them that causes a large in-rush
current at power on. Therefore it may be necessary to add some series resistance if the
cable length to the first set of strobes is not enough to limit the current. Add 10-20 ohms for
a total strobe current of <100mA, 8-10 ohms for 100mA, and 2 x RR1007 NTCs in series for
300mA-1A.
FIGURE 8.6.2
DUAL POLARITY OUTPUT FOR STROBES/AVI
+24V
NO
NC
C
Relay 1
Supervision Input
+
-
Alert +
NC
NO
NC
NO
C
C
Evac +
4k7
Strobes
Dual Pole Relay
(PA0730 or 8RM)
0V
Open
Collector
EVAC-
AVI
ALERT-