The **ALR-322-R/BL** is a high-performance **photoelectric lighting controller** (photocontrol) manufactured by TE Connectivity / ALR. It is designed to automatically manage outdoor lighting by sensing ambient light levels. --- ## 1. Core Technical Specifications | Feature | Specification | | :--- | :--- | | **Model** | ALR-322-R/BL | | **Input Voltage** | 105–285 VAC | | **Frequency** | 50/60 Hz | | **Load Rating (Tungsten)** | 1000 Watts | | **Load Rating (Ballast)** | 1800 VA | | **Turn-On Level** | 1.5 Foot-candles (fc) | | **Turn-Off Ratio** | 1.5:1 (approx. 2.25 fc) | | **Sensor Type** | Cadmium Sulfide (CdS) Cell | | **Housing Color** | Blue (Standard for 120V-277V range) | --- ## 2. Key Electronic Components The device consists of several critical electronic sub-assemblies that ensure durability and precision: ### A. The Sensor (CdS Photocell) The primary input component is a **Cadmium Sulfide (CdS)** photo-resistor. - **Function:** Its resistance changes based on light intensity. - **Logic:** High resistance in the dark (allowing current to trigger the circuit) and low resistance in daylight (shunting current away from the trigger). ### B. Thermal Actuator / Bimetal Switch Unlike digital smart controllers, the ALR series often utilizes a **thermal relay** mechanism. - **Operation:** When the sensor detects darkness, a small internal heater is activated. This heater warms a bimetallic strip which bends to close the power contacts. - **Benefit:** This provides a natural **time delay** (usually 30–60 seconds), preventing the light from flickering due to lightning or car headlights. ### C. Surge Protection (MOV) To protect the unit and the connected lamp from electrical spikes, the circuit includes a **Metal Oxide Varistor (MOV)**. - **Rating:** Typically rated for 160 Joules or higher. - **Function:** Absorbs transient voltage surges caused by lightning or grid switching. ### D. Physical Interface - **NEMA Plug:** It features a 3-prong twist-lock connector (ANSI C136.10 compliant). - **Contacts:** Solid brass legs for high conductivity and corrosion resistance. --- ## 3. Circuit Logic Summary ```mermaid graph LR A[Ambient Light] --> B[CdS Photocell] B --> C{Resistance Change} C --> D[Internal Heater] D --> E[Bimetal Contact Closure] E --> F[Load / Street Light ON] ``` --- ## 4. Application Notes * **Fail-Safe Mode:** The "R" in the model often denotes a "Fail-On" design. If the internal thermal element fails, the circuit is designed to stay closed so the light remains ON for safety until repaired. * **Durability:** The **BL (Blue)** housing is UV-stabilized polypropylene, protecting the internal electronics from moisture and sun degradation.