The **8702SDO2V03** is a specific model of a **Reversing Magnetic Starter** manufactured by Square D (Schneider Electric). It is part of the Type S NEMA-rated starter line. Below is a detailed breakdown of its electronic and electromechanical components. --- ## 1. Technical Specifications Overview This device is designed to start, stop, and reverse the direction of three-phase AC motors. | Feature | Specification | | :--- | :--- | | **NEMA Size** | Size 2 | | **Continuous Current Rating** | 45 Amperes | | **Configuration** | Reversing (Two Contactors) | | **Phase** | 3-Phase | | **Voltage (Coil)** | 240V AC @ 60Hz / 220V AC @ 50Hz | | **Enclosure Type** | Open (No external box) | | **Horsepower Rating** | 10 HP @ 200V, 15 HP @ 230V, 25 HP @ 460/575V | --- ## 2. Key Electronic & Mechanical Parts ### A. Magnetic Contactors (The "Heart") The unit consists of two mechanically interlocked contactors mounted on a single base: * **Forward Contactor:** Energizes the motor in the standard sequence. * **Reverse Contactor:** Swaps two of the incoming power leads to reverse the motor's rotation. * **Mechanical Interlock:** A physical safety mechanism that prevents both contactors from closing simultaneously, which would cause a phase-to-phase short circuit. ### B. The Coil (V03 Suffix) The **V03** in the part number indicates the specific voltage requirements for the electromagnetic coils: * **Voltage:** 240V AC. * **Function:** When energized, the coil creates a magnetic field that pulls the power contacts closed. If the voltage drops (undervoltage), the coil releases, acting as a safety disconnect. ### C. Contacts and Terminals * **Power Contacts:** Silver cadmium oxide contacts designed to handle high-inrush currents associated with inductive motor loads. * **Power Terminals:** Heavy-duty screw terminals for L1, L2, L3 (Line) and T1, T2, T3 (Load). ### D. Auxiliary Contacts The unit usually includes auxiliary contacts (often 1 N.O. per contactor) used for: * **Seal-in circuits:** Keeping the starter energized after the "Start" button is released. * **Electrical Interlocking:** An additional layer of safety using wiring to ensure the opposite coil cannot be energized. --- ## 3. Wiring Logic (Reversing) The internal wiring of the 8702SDO2V03 achieves reversal by switching the orientation of the phases. ```mermaid graph TD Line_Input --> Forward_Contactor Line_Input --> Reverse_Contactor Forward_Contactor --> Motor(T1-T2-T3) Reverse_Contactor --> Motor(T3-T2-T1) ``` --- ## 4. Maintenance & Replacement Parts Because this is a NEMA-rated device, it is fully serviceable. Common replaceable parts include: 1. **Contact Kits:** Replacement sets for when the silver contacts become pitted or burned. 2. **Replacement Coils:** If the coil burns out due to voltage spikes. 3. **Overload Relay (Sold Separately):** While the 8702 series is the starter, it is typically paired with a **9065 Thermal Overload Relay** to protect the motor from overcurrent.