System Sensor 2-Wire Photoelectric Smoke/Heat Detector with sounder-2WTA-B

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The 2WTA-B is a 2-wire, photoelectric i3 smoke detector with built in 135 degree F heat detection and sounder.
Brand: System Sensor
Part Number: 2WTA-B

Availability: In stock




Installation ease.
Throughout the i3 series, installation is simple with its installer-friendly base and plug-in design. The base accommodates a broad range of back box and direct mounting options and provides ample space for pre-wiring the device. To complete the installation, the i3 detector plugs into its base with a simple Stop-Drop ’N Lock action.

To reduce the likelihood of nuisance alarms, all i3 detectors are equipped with both drift compensation and smoothing algorithms. These capabilities minimize both short- and long-term causes of nuisance alarms, such as RF interference and dust accumulation. When connected to the 2W-MOD2 loop test/maintenance module or an i3 Ready™ panel, 2‑wire i3 detectors can generate a remote maintenance signal when in a maintenance or freeze trouble condition. To measure the sensitivity of any i3 detector, the SENS-RDR displays the reading, in terms of percent-per-foot obscuration, within seconds.

Instant inspection.
i3 has red and green LEDs to simplify local status indication during power-up, standby, alarm, maintenance, and freeze trouble conditions. When in alarm, i3 sounder models generate an 85 dB temporal tone. If connected to the RRS-MOD reversing relay/synchronization module, all i3 sounders on the loop will activate when one detector is in alarm. The RRS-MOD also synchronizes i3 sounder output to ensure a clear audible signal.

Should the application call for differentiating between a local and a general alarm, the i3 line offers an isolated thermal model, which initiates a local alarm when smoke is detected, and a general alarm when the thermal sensor is activated.

• 85 dB sounder
• Form C relay
• Isolated thermal sensor
• Plug-in design (base included)
• In-line terminals
• Flexible mounting options
• Stop-Drop ’N Lock™ attachment to the base
• Removable cover and chamber
• Remote maintenance signaling
• Drift compensation and smoothing algorithms
• Simplified sensitivity measurement
• Dual-color LEDs


Additional Info

Additional Info

Part Number 2WTA-B
What's in the box (1) System Sensor 2-Wire Photoelectric Smoke Detector with sounder-2WTA-B
Variant N/A


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Electrical Specifications

Operating Voltage
Nominal: 12/24 V non-polarized
2-wire: 8.5 V to 35 V
4-wire: 10 V to 35 V

Maximum Ripple Voltage
30% of applied voltage (peak to peak)
Standby Current
2-wire: 50 μA maximum average
4-wire: 50 μA maximum average

Peak Standby Current
2-wire: 100 μA
4-wire: n/a

Maximum Alarm Current
2-wire: 2WTA-B: 130 mA limited by control panel

Direct Power (Non-Reverse Polarity):
 130 mA limited by panel.

Reverse Polarity Power:
30 mA for the 2WTA-B in alarm; 12 mA for all
other 2WTA-B units on the loop. Add 25 mA
for the RRS-MOD reversing relay alarm current.

Alarm Contact Ratings
2-wire: n/a

Physical Specifications
Operating Temperature Range
32°F to 100°F (0°C to 37.8°C)

Operating Humidity Range
0 to 95% RH non-condensing

Thermal Sensor
135°F (57.2°C) fixed

Freeze Trouble
41°F (5°C)

Dimensions (including
base) 5.3 inches (134 mm) diameter, 2.0 inches
(51 mm) height

Approximate Weight
7.1 oz (200 g)

Sound Pressure Output
85 dBA (model 2WTA-B)

3½-inch octagonal back box, 4-inch octagonal
back box, single-gang back box, 4-inch square
back box with a plaster ring, direct mount to