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9.10 - Fire alarm interface methods
The most common method for interfacing fans with a fire alarm system is to provide a dry relay contact to each fan. In this scenario, the
relay coil is controlled by the Fire Alarm Control Panel (FACP) or a Notification Appliance Circuit (NAC). On newer systems, the relay
is replaced by an addressable Alarm Release Module (ARM). In all of these scenarios, the fan sees a dry contact inserted across a run
enable input to the fan controller. When the fan is turned on, it will enter an External Fault Trip (EF Fault). This is considered a “fail safe”
scenario, especially when the FACP, NAC, or ARM relay coil remains energized at all times to enable fan operation. Any circuit power
failure or alarm condition will result in a fan shutdown. The typical circuit layout is shown below.
R
R
R
1
2
ARM
ARM
ARM
FACP or NAC
panel output
V
SUPPLY
Fan Controller's ESFR
input terminals
Fan Controller's ESFR
input terminals
Fan Controller's ESFR
input terminals
Fan Controller's ESFR
input terminals
Fan Controller's ESFR
input terminals
Fan Controller's ESFR
input terminals
DATA
FACP
NC contact held open
for fan operation
NC contact held open
for fan operation
NC contact held open
for fan operation
NC contact held open
for fan operation
NC contact held open
for fan operation
NC contact held open
for fan operation
Supply
Common
The gateway provides an additional method of fire alarm system interface, which uses the run enable input on only one of the fan
controllers. The gateway monitors all enable inputs on all of the addressed and connected fan controllers, and issues a shutdown
command over the Modbus to the remaining controllers on the system if one of these inputs is reported as tripped.
The gateway
will not be able to see a fire alarm trip on a 0–10V daisy chained fan!
This method may not comply with National Fire Protection
Association (NFPA) Article 13 or other codes pertaining to fire alarm installation.
Consult all necessary parties and codes prior to
implementation.
R
FACP or NAC
panel output
V
SUPPLY
NC contact held open
for fan operation
Controller's
ESFR input
terminals
Modbus
Gateway Location
1
st
Gateway observes the
EF trip
2
nd
Gateway issues stop command to
remaining fans
Supply
Common
9 - Big
Ass
Fans Electrical Installation (cont.)
