Installation guide

VAR4 / VAR12 / VAR20 - Product Description
3.7.2.3 Positive Voltage Source (+VE going Input)
As per Contact Closure to Supply, but to an
alternatively switched voltage source, such as to
a suitable output from another piece of
equipment.
ROUTER
CONTACT INPUT
I
OPTO ON
WHEN CONTACT
CLOSED
+
-
12-40 V
FROM
REMOTE
EQUIPMENT
3.7.2.4 Fire Alarm Sounder Interface
The opto-isolated inputs may be used as a
reverse polarity sounder circuit interface to a Fire
Alarm system. In this DVA triggering method the
link between the fire panel and the VA system is
monitored at the Fire Panel by means of End of
Line Resistors. This is the current
recommendation of BS5839. The Fire panel
monitors the current flowing in the End of Line
Resistor. Reversing the polarity activates the
input.
The VAR Router does not have end of line
resistors fitted as standard, as the value required
varies according to the Fire Alarm system. The
desired value for a particular job must be
specified with the order. ASL can then factory-fit
the appropriate resistors.
Alternatively these resistors may be fitted local to
the VAR Router during installation. Note that in
this method the final connection into the VAR
Router is not monitored.
FIRE
SYSTEM
Cabling to Fire System
+V
-V
I
ROUTER
CONTACT INPUT
I
OPTO OFF
MONITORING
FIRE
SYSTEM
Cabling to Fire System
I
ROUTER
CONTACT INPUT
OPTO ON
ACTIVE
+V
-V
+
-
+
-
END OF LINE
RESISTOR
I
END OF LINE
RESISTOR
Issue: 03 complete, approved
Page 29 of 68