Fire alarm control panel

Addressable Fire Alarm Control Panel employ one or more Signalling Line Circuits - usually referred to as loops or SLC loops - ranging between one and thirty. Depending on the protocol used, a Signaling Line Circuit can monitor and control up to several hundred devices. Some protocols permit any mix of detectors and input/output modules, while other protocols have 50% of channel capacity restricted to detectors/sensors and 50% restricted to input/output modules. Each SLC polls the devices connected, which can number from a few devices to several hundred, depending on the manufacturer. Large systems may have multiple Signalling Line Circuits.[1][2]

Each device on an SLC has its own unique address, and thus the panel knows the state of each individual device connected to it. Common addressable input (initiating) devices include

• Smoke detectors
• Heat detectors (Rate of Rise and Fixed Temperature)
• Manual call points or manual pull stations
• Notification appliances
• Responders
• Fire sprinkler system inputs
• Switch status
  • Flow control
  • Pressure
  • Isolate
  • Standard switches
  • Monitor modules

Addressable output devices include

• (Warning System/Bell) relays
• Door holder relays
• Auxiliary (control function) relays
• Control modules
• Relay modules

Output devices are used to control a variety of functions such as

• Switching fans on or off
• Closing/opening doors
• Activating fire suppression systems
• Activating notification appliances
• Shutting down industrial equipment
• Recalling elevators to a safe exit floor
• Activating another fire alarm panel or communicator

Also known as "cause and effect", mapping is the process of activating outputs depending on which inputs have been activated. Traditionally, when an input device is activated, a certain output device (or relay) is activated. As time has progressed, more and more advanced techniques have become available, often with large variations in style between different companies.

This map display can be interpreted quickly (Germany)

Zones are usually made by dividing a building or area into different sections. Then depending on the specific zone, a certain number and type of device is added to the zone to perform its given job. Zones are a requirement of the National Building Code in Canada, and zones must be labelled and include red LEDs for fire zones, with amber LEDs for supervisory and trouble. The LED indicators are in addition to an LCD display, although this requirement is waived if the LCD has 8 or more lines of characters. Isolators are also required when wiring departs a zone and enters a new zone such as floor to floor and between firewalls.

Groups contain multiple output devices such as relays. This allows a single input, such as a smoke detector or alarm pull station to have only one output programmed to a group, which then maps to multiple outputs or relays. This enables an installer to simplify programming by having many inputs map to the same outputs, and be able to change them all at once, and also allows mapping to more outputs than the programming space for a single detector/input allows.

This is the part of a fire panel that may have the largest variation between different panels. This capability allows a panel to be programmed to detect fairly complex inputs. For instance, a panel could be programmed to notify the fire department only if more than one device has activated. It can also be used for staged evacuation procedures in conjunction with timers.

This resets the panel after an alarm condition. All initiating devices are reset, (except for pull stations which must be reset manually) and the panel is cleared of any alarm conditions. If an initiating device is still in alarm after the system is reset, such as a smoke detector continuing to sense smoke or a manual pull station still in an activated position, another alarm will be initiated, or in some cases the panel will refuse to reset until all the alarms have been reset/cleared. A system reset is often required to clear supervisory conditions. A system reset does not usually clear trouble conditions; most trouble conditions will clear automatically when conditions are returned to normal.

This function (also abbreviated as "ACK") is used to manually acknowledge an abnormal situation such as an alarm, trouble, or supervisory signal. This usually stops the panel "piezo" from sounding, and makes the activated (flashing) LED turn on steady ("go solid"). This also cancels the auto-evacuation timer (3–5 minutes depending on occupancy type) from advancing from first stage to second stage evacuation.

Depending on the configuration of the alarm system, this function (also known as "alarm silence" or "audible silence") will either deactivate the system's notification appliances completely, or will silence only the audible signals while strobe lights/visuals continue to operate (the latter condition is known as "audible silence"). Signal silence allows for easier verbal communication amongst emergency responders while responding to an alarm. This can also be used during building construction as a method of preliminary test, before the final full system test. Signal silence is usually used right after the emergency has been dealt with, and the building is ready to be reoccupied again. A system reset usually is done soon after.

This button (also known as "flash test") is still used on many panels to check the condition of the indicator lights (LEDs) themselves. A "Lamp Test" button is required by code on multi-zone panels installed in Canada. Many panels also do an automatic lamp test when the system is reset.

A "walk test" is a method of testing many fire alarm devices in a system, which saves time and requires fewer technicians at the location. Using "walk test", a single technician can simply walk around the building and activate any device they would like. Doing so will send a signal to the panel, which will either pulse the Notification Appliance Circuit (NAC) a certain number of times to indicate the zone on which the device is wired to, or simply sound the notification appliances for a few seconds, then automatically reset. A "silent walk test" will only flash the alarm light on the panel, thus not sounding the signals.

On panels that have this function, the drill function (also known as "manual evacuation") activates the system's notification appliances (NAC), often for purposes of conducting a fire drill. Using the drill function, a remote alarm is normally not transmitted to the fire department or monitoring center, as the auxiliary relays for this function are not activated. However, building personnel often notify these agencies in advance anyway, in case an alarm is inadvertently transmitted.

This button, or input terminals connected to an external timer switch, will sound the notification appliances briefly in a different cadence from the fire alarm sequence. It is used to signify class change or lesson breaks in schools, and allows the fire alarm system to be used instead of a separate class bell system. This ensures pupils are familiar with the sound of the alarm, and means the notification appliance circuits are tested several times a day.

Also known as "Fire" or "General Alarm". This indicator is lit when an alarm condition exists in the system, initiated by smoke detectors, heat detectors, sprinkler flow switches, manual pull stations, manual call points, or otherwise. Along with the indicator on the panel, notification appliances, such as horns and strobes, are also activated via the Notification Appliance Circuit (NAC), signalling to building occupants that they must evacuate. In an alarm condition, the fire alarm panel indicates where the alarm originated. The alarm panel can be reset once the device which initiated the alarm has been reset, such as returning the handle of a manual pull station to its normal position.

Also known as "Signals Silenced" or "Alarm Silenced", this indicator is used in conjunction with the "Alarm" indicator. It indicates that the fire alarm panel is still in an alarm condition, but that notification appliances (NACs) have been silenced. While the alarm is silenced, other functions in an alarm condition continue to operate, such as emergency service for elevators, stairway pressurization, and ventilation functions. A new alarm initiation signal while the alarm is silenced will take the panel out of Silence and reactivate the notification appliances.

Also known as "Manual Evacuation" or "Evacuate". On panels containing this function, the "Drill" indicator shows that the alarm condition was activated from the fire alarm panel, often in order to conduct a fire drill. When an alarm is initiated for a drill, the fire department or monitoring company is usually not notified automatically.

This LED is often used in conjunction with a two-stage system, in which the panel requires two devices to be activated (and/or a predetermined time limit to run out after one device is activated) in order to go into full alarm. This is mostly used in areas where false alarms are a common problem, or in large applications (such as hospitals) where evacuating the entire building would not be efficient. The prealarm LED is lit when one device has tripped. The prealarm LED may also be used if an addressable smoke detector registers low levels of smoke in the detection chamber, but not enough to trigger a full alarm.[3] Depending on the system's layout, the Notification Appliance Circuit (NAC) may or may not activate for prealarm conditions. In a two-stage system, the NACs are typically coded to a special first-stage coding, or in some situations where a loud alarm signal could be disruptive, chimes will activate. If there is a voice evacuation system, it will usually instruct building occupants to await further instructions while the alarm is being investigated.

Also known as "Fault" or "Defect". When held steady or flashing, it means that a trouble condition exists on the panel. Trouble conditions are often activated by a contaminated smoke detector or an electrical problem within the system. Trouble conditions are also activated by a zone being disabled, a circuit or NAC being disabled, low power on the backup battery, disabling of a notification appliance, ground faults, or short or open circuits. Usually the alarm panel's sounder will activate if a trouble condition exists, though older systems would sometimes activate a bell or other audible signal connected to the panel. In a trouble condition, the panel displays the zone or devices causing the condition. Usually, the "Trouble" indicator goes out automatically when the situation causing the trouble condition is rectified; however in some systems the panel must be manually reset to clear the trouble alarm. Some panels have more specific indicators such as "Trouble-PSU" which shows when the panel itself is compromised, and "Trouble-Bell" or "NAC Trouble" ("Sounder Fault" on UK panels) which shows that the notification appliances are not functioning or connected correctly. On most panels, an acknowledge button is pressed to turn off the panel's sounder.

This signal indicates that a portion of the building's fire protection system has been disabled (such as a fire sprinkler control valve being closed, and consequently a sprinkler tamper switch being activated), or less frequently, that a lower-priority initiating device has been triggered (such as a duct smoke detector). Depending on the system's design, the supervisory point may be latching, meaning the panel must be reset to clear the supervisory condition, or non-latching, meaning the indicator automatically goes out when the condition has cleared. However, some panels require a manual reset regardless of whether the supervisory point is latching or non-latching.

Also known as "Normal". When this (usually green) indicator is lit, power is being provided to the system from the building's electrical system, and not from the backup battery. When an AC power condition changes, the Trouble indicator comes on and the AC power indicator either goes off or starts flashing ,and the panel alerts building personnel of a power failure. If the AC power indicator is lit without any other indicators also lit, then the system is in a normal non-alarm condition. If no LEDs are lit, there is no power source feeding the panel.

This is used to tell the operator that the panel's DC power (batteries) is being charged or used. While relying on DC backup power, the system remains in a fault condition.

This LED is on when the battery charger is in the high rate charge state, in which the charger voltage is boosted to charge batteries faster after they have been depleted.