The **FTR-K3JB009W-HC** is a high-power, PCB-mount electromechanical relay manufactured by **Fujitsu**. It is specifically designed for high-current applications, such as the charging circuits of Electric Vehicles (EV/PHEV) and industrial power supplies. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Contact Form** | 1 Form A (SPST-NO) | | **Nominal Coil Voltage** | 9V DC | | **Rated Contact Current** | 33A (High Capacity) | | **Maximum Switching Voltage** | 300V AC | | **Coil Power Consumption** | Approx. 900mW | | **Dielectric Strength** | 5,000V AC (between coil and contacts) | | **Surge Strength** | 8,500V | | **Terminal Type** | PCB Through-hole | --- ### 2. Electronic Component Breakdown #### A. The Coil (Actuator) * **Voltage (009W):** This specific model operates on a **9V DC** control signal. * **Power Efficiency:** While it consumes 900mW during actuation, it is designed for thermal stability to prevent the relay from overheating during continuous duty cycles. #### B. The Contacts (Switching Element) * **High Capacity (HC):** The "HC" suffix indicates high-current capability. Unlike standard relays that handle 10A-16A, this component is rated for **33A**. * **Contact Material:** Usually composed of Silver Alloy (AgNi or AgSnO2) to resist "welding" (sticking) and electrical pitting caused by high-current arcing. * **Gap:** Features a wide contact gap (approx. 1.5mm or more depending on specific safety standards) to ensure safe insulation when the circuit is open. #### C. The Housing (Insulation) * **Reinforced Insulation:** The physical construction provides a high clearance and creepage distance, allowing it to meet stringent safety standards (like IEC 60664-1). * **Flammability:** The plastic casing is typically UL94V-0 rated (self-extinguishing). --- ### 3. Common Applications * **On-board Chargers (OBC):** Used in Electric Vehicles to manage the flow of AC power to the battery. * **Photovoltaic (PV) Inverters:** Switching DC to AC in solar energy systems. * **Uninterruptible Power Supplies (UPS):** Managing high-load battery backups. * **Industrial Automation:** Controlling heavy motors or heaters. --- ### 4. Part Number Decoder `FTR-K3` (Series) + `J` (Contact Rating) + `B` (Sealing Type) + `009` (9V Coil) + `W` (Contact Material) + `HC` (High Capacity)