• Home
  • Electronics Expo
  • Quality Articles
  • How Does the 1/2″ OM-200-QCV Disc Thermostat Manual Reset Work

    Maintaining a comfortable temperature in a circuit is crucial, and your trusty OM-200-QCV thermostat plays a vital role in achieving that comfort. However, even the most reliable devices can experience occasional hiccups, requiring a manual reset.

    Let’s find out how this thermostat manual reset disc works.

    Bi-Metal Temperature Controls

    Selco’s 1/2″ OM-200-QCV Disc Thermostat relies on bi-metal temperature controls, a technology that has proven highly reliable in various applications. The switch employs a temperature-sensitive bi-metal disc, which is electrically isolated from the switch itself.

    This ingenious design ensures the safety and accuracy of temperature regulation. The switch contacts are usually closed and open when the surface or ambient temperature reaches the pre-set point.

    The circuit remains open until the manual reset button is depressed, typically around 30% below the operating temperature.

    What is QCV?

    The OM-200-QCV’s functionality is key to its QCV technology. This acronym stands for Quick-Close-Valve, indicating the thermostat’s swift response to temperature changes. The Quick-Close-Valve is crucial in applications where rapid temperature control is essential, such as preventing overheating or maintaining precise temperature levels.

    Applications of OM-200-QCV Disc Thermostat

    The versatility of the OM-200-QCV is evident in its broad spectrum of applications. This thermostat finds its place in everyday appliances and industrial equipment, ensuring optimal performance and safety. Some common applications include:

    • Warming Equipment
    • Fan Heaters
    • Vending Machines
    • Dryers
    • Washing Machines
    • Electric Heaters
    • Furnaces
    • Boilers
    • Microwave Ovens
    • Water Heaters
    • Fireplaces

    Operating Temperature Range

    A crucial aspect of any thermostat is its operating temperature range. The OM-200-QCV excels in this regard, with a UL-approved range of 120˚-302˚F (49˚-150˚C) and a non-UL-approved range of 303˚-320˚F (150˚-160˚C). This wide temperature range makes it suitable for various applications across different industries.

    Electrical Ratings

    The electrical ratings of the OM-200-QCV further highlight its adaptability to diverse electrical systems. The device comes in two variations: Silver 603U-H and Gold 603K. The Silver 603U-H variant supports:

    • 125VAC, 15A, Resistive, 6,000 Cycles
    • 250VAC, 10A, Resistive, 6,000 Cycles
    • 120VAC, 12A, Inductive, 6,000 Cycles
    • 120VAC, 5.8FL, 34.8LRA, 6,000 Cycles
    • 240VAC, 2.9FLA, 17.4 LRA, 6,000 Cycles

    On the other hand, the Gold 603K variant supports:

    • 30VDC, 1A, Resistive, 6,000 Cycles
    • 120VAC, 125VA (Pilot Duty), 6,000 Cycles

    These diverse electrical ratings ensure compatibility with various systems, making the OM-200-QCV a versatile application choice.

    Manual Reset Mechanism: A Closer Look at Precision Control

    One outstanding feature of the OM-200-QCV is its thoroughly engineered manual reset mechanism. This feature distinguishes the device and plays a crucial role in applications that require human intervention and precise control.

    Circuit Operation:

    As the ambient or surface temperature reaches the preset point, the OM-200-QCV’s contacts promptly open, interrupting the circuit. This instantaneous response to temperature fluctuations ensures the connected system is safeguarded from overheating or other potentially hazardous conditions. They work precisely like circuit breakers.

    Manual Reset Button:

    Following the circuit interruption, the device remains resettable until the manual reset button is engaged. This button, strategically placed on the thermostat, empowers users to manually reset the switch, reinstating regular operation. This manual intervention is particularly valuable when a system override is necessary, allowing for a more hands-on approach to temperature control.

    Temperature Set Point:

    The manual reset button is designed to be depressed at approximately 30% below the operating temperature. This deliberate threshold ensures the system doesn’t reset prematurely, maintaining a safety buffer to prevent rapid cycling. The manual reset point serves as a fail-safe mechanism, preventing unintentional resets and ensuring that human intervention aligns with the operational requirements of the connected equipment.

    Applications of Manual Reset:

    The manual reset feature is useful in various real-world applications. For instance, in industrial processes where abrupt temperature changes could compromise product quality or safety, manually resetting the thermostat allows for meticulous control. In heating systems, the manual reset ensures that the equipment doesn’t resume operation until it’s confirmed safe, preventing potential fire hazards or other malfunctions.

    Enhanced Safety and Control:

    This manual reset capability enhances the OM-200-QCV’s safety profile, providing an additional layer of protection against unexpected temperature variations. The hands-on control afforded by the manual reset feature also proves beneficial during maintenance activities, allowing technicians to perform checks and adjustments without compromising the system’s integrity.

    Integrating Technology and Human Control:

    In an era dominated by automation and intelligent technologies, the manual reset feature harmoniously integrates technology and human control. While the thermostat operates autonomously based on temperature conditions, the manual reset button acknowledges the need for human oversight, especially in critical applications where precision and safety are non-negotiable.

    Insulation Resistance and Circuit Resistance

    To ensure the longevity and reliability of the device, the OM-200-QCV boasts impressive insulation and circuit resistance values. With insulation resistance equal to or greater than 100mΩ (measured with a 500VDC Megger) and circuit resistance less than or equal to 50mΩ (initial value) for the Silver 603U-H variant and less than or equal to 10mΩ (initial value) for the Gold 603K variant, the device is designed to withstand the test of time.

    Dielectric Strength

    The OM-200-QCV’s dielectric strength is a testament to its robust design. The Silver 603U-H variant can withstand 1,500 for one minute, while the Gold 603K variant can withstand 1,200 for the same duration.

    This ensures the device can endure high-voltage conditions without compromising its functionality.


    The 1/2″ OM-200-QCV Disc Thermostat with Manual Reset is the pinnacle of temperature control technology. Its innovative QCV technology, wide operating temperature range, and versatile applications have earned its place in various industries.

    The manual reset feature adds an extra layer of control, making it a reliable choice for critical systems where precision and safety are paramount. As a Selco product manufactured in an ISO 9001-certified factory, users can trust this thermostat’s safe and reliable operation. The OM-200-QCV is a beacon of temperature control excellence in everyday appliances or industrial equipment.

    Moreover, always buy electronic components from reputable distributors since they are safe to use. One such distributor is WIN SOURCE, a distributor pioneer who offers many products—check them out today!


    DISQUS: 0