The **ALR-114-R** is a specific type of **Photocontrol (Cell)** used primarily in outdoor lighting systems, such as street lights and area security lighting. It is designed to automatically turn fixtures on at dusk and off at dawn based on ambient light levels. Below is an explanation of its electronic components and specifications. --- ### 1. Core Electronic Specifications The "R" in ALR-114-R often signifies a specific mounting or relay configuration within the ALR series produced by TE Connectivity (formerly Tyco/Amerace). | Feature | Specification | | :--- | :--- | | **Input Voltage** | 105-130V AC (Standard 120V) | | **Load Rating (Tungsten)** | 1000 Watts | | **Load Rating (Ballast)** | 1800 VA | | **Frequency** | 50/60 Hz | | **Operating Temperature** | -40°C to +70°C | | **Turn-on Level** | 1.5 Foot-candles (Standard) | --- ### 2. Internal Components The device utilizes a mix of thermal and optical components to manage high-voltage loads safely. #### A. The Cadmium Sulfide (CdS) Cell The "eye" of the unit. This is a **Light Dependent Resistor (LDR)**. * **In Light:** Resistance drops, allowing current to flow to the internal heating element. * **In Dark:** Resistance increases, cutting current to the heater and allowing the mechanical switch to close. #### B. Thermal Bimetallic Switch (Relay) Unlike modern instant-on digital sensors, the ALR-114-R typically uses a **thermal relay**. * It consists of a bimetallic strip wrapped in a heater wire. * **Delay Mechanism:** This design provides a built-in time delay (usually 30-60 seconds). This prevents "flicker" caused by lightning strikes or car headlights passing by. #### C. Surge Protection (MOV) Most ALR units include a **Metal Oxide Varistor (MOV)**. This electronic component protects the light fixture and the internal sensor from voltage spikes caused by lightning or grid instability. --- ### 3. Physical Interface: The NEMA Plug The ALR-114-R uses a standard **3-prong twist-lock** connection, adhering to ANSI C136.10 standards. | Pin | Function | Wiring Color Code (Internal) | | :--- | :--- | :--- | | **Large Blade** | Neutral | White | | **Small Blade 1** | Line (Power In) | Black | | **Small Blade 2** | Load (Power Out to Lamp) | Red | --- ### 4. Wiring Diagram (Logical Representation) ```text [Line Hot] ----( Black )---- [ Photocontrol ] ----( Red )---- [ Light Fixture ] | [Line Neutral] --( White )----------+------------------------ [ Light Fixture ] ``` --- ### 5. Failure Modes * **Fail-On:** The ALR-114-R is designed to fail in the **ON** position. If the internal heater or cell fails, the light stays on during the day, alerting maintenance that the part needs replacement. * **Clouding:** The clear UV-stabilized polycarbonate housing can degrade over years, causing the sensor to think it is always dark.