The **FRS-55-R** is an addressable photoelectric smoke detector manufactured by **Hochiki**. It is specifically designed to be part of an intelligent fire alarm system, communicating with a central control panel to report smoke levels and status. --- ### ## Technical Specifications Below are the primary electronic and operational characteristics of the FRS-55-R: | Feature | Specification | | :--- | :--- | | **Operating Voltage** | 17.0 - 41.0 VDC | | **Current Consumption (Standby)** | 390 $\mu$A (Typical) | | **Current Consumption (Alarm)** | 8 mA (Maximum) | | **Transmission Method** | DCP (Digital Communication Protocol) | | **Detection Method** | Photoelectric (Light Scattering) | | **Operating Temperature** | 32°F (0°C) to 115°F (46°C) | | **Relative Humidity** | 95% RH Non-Condensing | --- ### ### Key Electronic Components & Functions 1. **Photoelectric Sensing Chamber:** * **Infrared LED:** Emits a beam of light into a dark chamber. * **Photodiode:** Positioned at an angle to the LED. Under normal conditions, no light reaches the photodiode. When smoke particles enter, light scatters and hits the sensor, triggering the alarm signal. 2. **Addressing Circuitry:** * The device does not use mechanical DIP switches for addressing. Instead, the address is stored electronically in **EEPROM**. * It uses a handheld programmer (like the DPU) to assign a unique address (1-127) to each unit. 3. **Digital Communication Protocol (DCP):** * The "brains" of the unit utilize Hochiki’s DCP, which allows for high-speed, noise-immune communication with the fire alarm control panel. * This allows the panel to perform "drift compensation," automatically adjusting the sensitivity as the sensor gets dirty over time. 4. **LED Indicators:** * **Blinking Green:** Indicates the device is polling correctly and communicating with the panel. * **Steady Red:** Indicates the device has reached its alarm threshold. --- ### ### Installation & Wiring Logic The FRS-55-R is typically installed on a compatible base (such as the YBN-NSA-4). The wiring follows a Signaling Line Circuit (SLC) loop: ```mermaid graph LR A[Control Panel] -- SLC + / - --> B(Detector 1) B -- SLC + / - --> C(Detector 2) C -- SLC + / - --> D(Detector 3 / End of Line) ``` **Wiring Notes:** * The SLC loop provides both **power** and **data** to the sensor. * Polarity must be observed for the device to function correctly within the digital loop. ---