The **MH22TCD-R** is a specific model of a **Bimetallic Disc Thermostat** (thermal switch) manufactured by companies like **Microtherm**. These components are used primarily for thermal protection and temperature control in industrial and consumer electronics. --- ### 1. Technical Specifications The part number breaks down into specific technical characteristics. Below is a summary of the typical properties for this series: | Property | Description | | :--- | :--- | | **Component Type** | Bimetallic Temperature Switch (Thermostat) | | **Contact Type** | Normally Closed (NC) or Normally Open (NO) | | **Current Rating** | Typically up to 2.5A / 250V AC | | **Housing Material** | Plastic (Thermoset) or Ceramic base | | **Terminal Style** | Radial Leads (Tinned Copper) | | **Mounting** | PCB Mounting or Surface Contact | --- ### 2. Functional Principles The MH22TCD-R operates based on the physical properties of two dissimilar metals bonded together (a bimetallic strip/disc): 1. **Sensing:** The disc is calibrated to react to a specific "Switching Temperature." 2. **Deformation:** When the ambient temperature reaches the set point, the internal disc "snaps" or bends due to the different expansion rates of the metals. 3. **Circuit Action:** This snap action physically moves the electrical contacts, either opening the circuit (to stop heating) or closing it (to trigger a cooling fan). 4. **Reset:** Once the temperature drops below a certain threshold (hysteresis), the disc snaps back to its original position. --- ### 3. Key Applications Because of its small form factor and reliability, the MH22TCD-R is commonly found in: * **Power Supplies:** To prevent overheating of transformers or MOSFETs. * **Electric Motors:** Embedded in windings to shut down the motor if it stalls or overheats. * **Battery Packs:** Protecting Li-ion cells from thermal runaway during charging. * **Small Appliances:** Coffee makers, hair dryers, and heaters as a secondary safety limit. --- ### 4. Part Number Interpretation (General) While specific suffix codes can vary by manufacturer, "MH22" generally refers to the **Small-size series**, "T" often indicates **Terminal configuration**, and "R" frequently denotes **RoHS Compliance**.