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Document: LT0400
10.2 AS1668 Fan Control Flows
The control of ventilation and air conditioning in buildings under fire mode is described in
AS/NZS 1668.1:1998. This requires fire alarm detection to activate the fan to prevent the
smoke from spreading to other zones. In another topology - when fire is detected it is
required to stop the fan to prevent smoke spreading to other areas of the building.
The following fan control example describes the situation where on fire detection it is desired
to activate the fan to spill the smoky air outside – an Exhaust Fan. It assumes that the
4100U is directly controlling the Fans on Alarm. In most cases, the 4100U send General Trip
and Zone Trips to the Mechanical Services Board/s, which controls the Fans functionality
when the manual controls are in the Auto Position.
Note: AS1668.1 requires that Fans continue to operate in Auto (after an alarm has
cleared and been reset) until the A/C Reset button is pressed or a Manual Control is
activated and in the case of Supply Air and Stair Pressurization Fans, stop the fan when
smoke is detected in the supply side Air Duct. The Fan shall restart 60 seconds after the
Duct Probe (Detector) has cleared of smoke / returned to normal and immediately if the
zone is isolated. Supply air duct detectors shall be non-latching / self resetting and shall
indicate on the FFCP (Fire Fan Control Panel). S/A Detectors are programmed as a
Utility point type.
Fan Activate in AS1668 Auto Position:
1. The 4100U-S1 panel goes into Alarm and Custom Control determines that the fan
should start.
2. The 4100U-S1 panel sends to the Multi-Point I/O a control to close the relay that
controls the fan to start.
3. The Multi-Point I/O closes the relay to start the fan.
4. The fan runs, and air flows through the duct.
5. An air flow sensor in the duct sends status to the panel via the Multi-Point I/O that the
air is flowing.
6. The panel controls the AS1668 module to turn the Red "ON" LED to ON and the
Green "OFF" LED to OFF.
Fan Stop in AS1668 Auto Position:
1. The 4100U-S1 panel has reset and the A/C Reset button has been pressed.
2. Custom Control determines that the fan should stop.
3. The 4100U-S1 panel commands the Multi-Point I/O to open the relay that controls
the fan.
4. The Multi-Point I/O opens the relay to stop the fan.
5. The fan stops and air does not flow through the duct.
6. An air flow sensor in the duct sends to the panel via the Multi-Point I/O that the air
flow is OFF.
7. The panel controls the AS1668 module to turn the Green "OFF" LED to ON and the
Red "ON" LED to OFF.
AS1668 Fan Manual Start:
1. The 4100U-S1 panel receives indication from its AS1668 board that Fan #n rotary
switch state has changed to „Start‟.
2. The 4100U-S1 panel commands the Multi-Point I/O to close the relay that controls
the fan.
3. The Multi-Point I/O closes the relay to start the fan.
4. The fan runs and air flows through the duct.
5. An air flow sensor in the duct sends to the panel via the Multi-Point I/O an indication
that the air flow is ON.
6. The panel controls the AS1668 to turn the Red "ON" LED to ON and the Green
"OFF" LED to OFF.
Issue 1.4
15 December 2010
4100U-S1 Programming Guide
AS1668 Fan Controls
Page 10-3
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