4 Conventional Products—2412AT, 2424AT, and 2424AIT Direct 4-Wire Smoke Detectors
The 2412AT, 2424AT, and 2424AIT photoelectronic smoke detectors are
designed to provide open area protection and to be used with UL Listed
4-wire control panels.
The 2412AT operates at 12 VDC, and the 2424AT and 2424AIT operate
at 24 VDC. The sensor in this detector operates on the light scattering
principle and features a unique photo-optic sensing chamber that provides
good smoke entry while minimizing the effects of ambient light.
These detectors also provide restorable 135°F fixed-temperature heat
detection. The 2412AT and 2424AT heat detection unit is integrated
with the photoelectronic sensor while the 2424AIT’s heat detection
unit is isolated from the photoelectronic smoke sensor and can be
monitored separately.
In addition, a piezoelectric horn in each detector produces an interrupted,
85 dBA minimum tone when the individual detector alarms or when the
supply voltage polarity is reversed.
A Light Emitting Diode (LED) on each detector lights to provide a local
alarm indication and will remain on when the supply polarity is reversed.
A screw terminal is provided for a remote LED annunciator optional
accessory (RA400Z). These detectors are listed to UL 268 and are
latching-type system detectors. The alarm can be reset only by momentary
power interruption. For testing, these detectors have a test switch or may
be tested by inserting a calibrated test card in a test slot after removing the
detector’s cover.
Each detector contains one Form-A (SPST; NO) contact for connection to
an alarm-initiating circuit. Supervision of the detector power is
accomplished by installing a power supervisory End-of-Line (EOL) relay
module (A77-716B) at the end of the detector power circuit. When power
is applied to and through the detectors, the EOL power supervisory
module is energized. Its relay contacts close and provide a closed series
circuit in the control panel’s alarm Initiating Device Circuit (IDC).
A power failure or break in the detector power circuit de-energizes the
EOL module. The relay contacts open and trigger a trouble signal at the
control panel.
General
Description
