The **DR10D561K** is a specific model of a **Metal Oxide Varistor (MOV)**, a passive electronic component used primarily for surge protection and voltage clamping in power supplies and industrial equipment. ### 1. Component Overview A varistor is a voltage-dependent resistor. Under normal operating voltages, it has a high electrical resistance. When a high-voltage spike (like lightning or switching surges) occurs, its resistance drops sharply, shunting the excess energy away from sensitive downstream components. ### 2. Part Number Breakdown (DR10D561K) The alphanumeric code follows a standard industry format for varistors: | Code Segment | Meaning | Description | | :--- | :--- | :--- | | **DR** | Series/Brand | Manufacturer-specific series (likely "Dongnan" or similar). | | **10** | Disc Diameter | Represents a **10mm** diameter disc. Larger discs handle more energy (Joules). | | **D** | Shape | Indicates a **Disc** (circular) shape. | | **561** | Varistor Voltage | The nominal voltage at 1mA. Calculated as **56 x 10^1 = 560V**. | | **K** | Tolerance | Indicates a **±10%** tolerance on the 560V rating. | --- ### 3. Key Technical Specifications Based on the standard parameters for a 10D561K MOV: * **Varistor Voltage ($V_{1mA}$):** 560V (Range: 504V to 616V). * **Maximum AC Voltage ($V_{RMS}$):** Approximately **350V AC**. * **Maximum DC Voltage ($V_{DC}$):** Approximately **460V DC**. * **Clamping Voltage ($V_c$):** The maximum voltage seen by the load during a surge, typically around **920V** at a specific peak current. * **Surge Current (8/20µs pulse):** Typically rated for **2,500A** (2.5kA). * **Energy Absorption:** Usually around **60 to 80 Joules**. --- ### 4. Typical Applications The DR10D561K is commonly found in circuits operating on **220V/230V AC mains** because its 560V breakdown threshold is high enough to avoid nuisance tripping from standard AC fluctuations but low enough to protect against spikes. * **Switching Power Supplies (SMPS):** Protecting the input bridge rectifier. * **Home Appliances:** Refrigerators, washing machines, and televisions. * **LED Drivers:** Protecting the driver circuitry from grid instability. * **Industrial Controllers:** Protecting PLC inputs and relay coils. --- ### 5. Circuit Symbol and Installation In a schematic, a varistor is represented by a resistor symbol with a diagonal line and a "V" or the letter "Z" (representing Zinc Oxide). ```text L (Line) o-------[ FUSE ]-------+------- To Load | [ MOV ] | N (Neutral) o-------------------+------- To Load ``` *Note: It is standard practice to place a fuse before the MOV. If the MOV fails "short" due to a massive surge, the fuse will blow, preventing a fire hazard.*