The **ALR-413-R/BL** is a specialized electronic component, typically classified as a **NEMA Locking-type Photocontrol (Photocell)** designed for outdoor lighting systems, such as street lights and area lighting. ### 1. Technical Specifications The device acts as an automated switch that triggers lighting based on ambient light levels. Below are the key technical parameters: | Feature | Specification | | :--- | :--- | | **Input Voltage** | 105-305 VAC (Multi-volt operation) | | **Load Rating (Tungsten)** | 1000 Watts | | **Load Rating (Ballast)** | 1800 VA | | **Turn-On Light Level** | ~1.5 Foot-candles (fc) | | **Turn-Off Light Level** | ~2.25 Foot-candles (fc) | | **Operating Frequency** | 50/60 Hz | | **Sensor Type** | Cadmium Sulfide (CdS) or Solid State | --- ### 2. Core Electronic Components The internal architecture of the ALR-413-R/BL consists of several critical electronic parts: #### A. Light Sensor (Photocell) Most variants use a **Cadmium Sulfide (CdS) cell**. This is a photo-resistor whose resistance decreases as light intensity increases. When the sun sets, the resistance rises, triggering the internal circuit to close the relay. #### B. Electromagnetic Relay Unlike solid-state switches, these units often use a physical **Relay**. This allows the device to handle high-wattage inductive loads (like HID or LED drivers) without excessive heat buildup. #### C. Surge Protection (MOV) To protect the light fixture from voltage spikes and lightning strikes, the unit includes a **Metal Oxide Varistor (MOV)**. This component shunts excess voltage to ground, preventing damage to the internal circuitry. #### D. Time-Delay Circuit A thermal or electronic **time-delay mechanism** is included. This prevents the light from flickering off due to temporary light flashes (such as car headlights or lightning). --- ### 3. Physical Interface (NEMA Plug) The "R/BL" designation refers to the physical housing and color (usually Blue). The base uses a **3-prong NEMA locking plug** (ANSI C136.10 standard): 1. **Line (Black):** Power input from the grid. 2. **Neutral (White):** Common connection. 3. **Load (Red):** Switched power output to the lamp. --- ### 4. Wiring Diagram Representation ```mermaid graph LR A[AC Line In] --> B[Photocontrol ALR-413] B --> C[MOV / Surge Protection] C --> D[Light Sensor] D --> E[Relay Switch] E --> F[Output to Lamp/Load] ```