The **LR2D3553_V01** is a specific model of an **Overload Thermal Relay**, typically associated with the Schneider Electric TeSys D range (or compatible series). It is an electromechanical protection device used to protect AC motors against overloads and phase failures. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Model Number** | LR2D3553 (V01 Revision) | | **Thermal Adjustment Range** | 23.0 A to 32.0 A | | **Compatible Contactors** | LC1D25, LC1D32, LC1D38 | | **Network Type** | AC / DC | | **Trip Class** | Class 10A (Trips within 2-10s at 7.2x setting) | | **Auxiliary Contacts** | 1 NO (Normally Open) + 1 NC (Normally Closed) | --- ### 2. Main Internal Components The relay functions using several key electromechanical parts rather than pure solid-state electronics: * **Bimetallic Strips:** The core sensing element. Three strips (one per phase) expand when heated by current. If the current exceeds the dial setting, the physical deformation triggers the trip mechanism. * **Current Adjustment Dial:** A potentiometer-style dial on the front face that allows the user to set the exact Amperage (between 23A and 32A) based on the motor's Full Load Amps (FLA). * **Trip Mechanism:** A spring-loaded linkage that snaps open the NC contact to kill power to the contactor coil when an overload is detected. * **Differential Mechanism:** Detects **Phase Loss**. If one bimetallic strip expands significantly less than the others, the differential bar slides and trips the unit faster to prevent motor burnout. --- ### 3. Operational Interface The **V01** revision typically features the following interface components: 1. **Stop Button:** Red button that manually opens the NC contact to stop the motor. 2. **Reset Button:** Blue button used to restore the circuit after a trip. It can often be switched between **Manual (H)** and **Automatic (A)** reset modes. 3. **Test Selector:** A hidden or recessed slider used to simulate a trip to test the auxiliary wiring. 4. **Sealable Cover:** A transparent plastic flap that prevents unauthorized changes to the current settings. --- ### 4. Typical Wiring Diagram ```mermaid graph TD Line[3-Phase Power] --> Relay[LR2D3553] Relay --> Motor[Electric Motor] subgraph Control_Circuit NC[95-96 NC Contact] -- Series --> Coil[Contactor Coil] NO[97-98 NO Contact] -- Parallel --> Lamp[Fault Indicator] end ``` ---