The **WJM-155-R/Q** refers to a specific type of **Hermetically Sealed Relay**, typically utilized in demanding environments such as aerospace, military, and high-reliability industrial automation. These components are designed to switch electrical loads while being protected from environmental factors like humidity, dust, and oxidation. Below is a detailed breakdown of the electronic parts and specifications associated with this series. --- ### 1. Technical Specifications The WJM series generally follows standard military/industrial relay architectures. The "R/Q" suffix usually denotes specific mounting styles or screening levels. | Feature | Description | | :--- | :--- | | **Contact Arrangement** | Typically 2PDT (2 Form C) or 4PDT (4 Form C) | | **Coil Voltage** | Usually 28V DC (Standard for Aerospace/Military) | | **Contact Rating** | High-power switching (often up to 5A - 10A depending on load type) | | **Enclosure** | Hermetically sealed metal can (Filled with inert gas) | | **Operating Temp** | -65°C to +125°C | | **Life Expectancy** | ~100,000 operations at rated load | --- ### 2. Key Internal Components A relay of this caliber consists of several precision-engineered electronic and mechanical parts: #### A. The Electromagnetic Coil * **Winding:** Fine copper wire wound around a core. When energized, it creates a magnetic field. * **Core:** A soft magnetic material that concentrates the flux to move the armature. #### B. The Contact System * **Stationary Contacts:** Fixed terminals made of silver-cadmium oxide or gold-plated alloys to prevent "welding" and minimize contact resistance. * **Movable Armature:** A mechanical lever moved by the magnetic field that bridges or breaks the electrical connection. #### C. The Header and Pins * **Glass-to-Metal Seal:** The pins at the base are insulated from the metal casing using glass preforms. This ensures the vacuum-tight integrity of the unit. * **Hook or Plug-in Terminals:** Depending on the "R" or "Q" designation, the pins may be designed for solder hooks or PCB mounting. --- ### 3. Functional Identification (R/Q Designations) In the context of these specific relays, the letters often signify: * **R:** Often denotes **Solder Hook** terminals for manual wiring in chassis. * **Q:** Often denotes **Threaded Studs** or specific **Plug-in** mounting brackets for high-vibration environments. ### 4. Typical Application Circuit The WJM-155 is used as a bridge between low-power control logic and high-power actuators. ```yaml Control Side: 28V DC Signal -> Coil -> Ground Load Side: High Current Source -> COM Terminal -> NO/NC Terminals -> Motor/Solenoid ``` --- ### 5. Why "Hermetically Sealed"? Electronic parts like the WJM-155-R/Q are sealed to prevent **Arcing** and **Corrosion**. At high altitudes or in harsh environments: 1. **Moisture** cannot enter to freeze or corrode the contacts. 2. **Contact Arcing** is reduced because the internal atmosphere is controlled (nitrogen/helium mix), extending the life of the internal electronics.