![]() ![]() The most important consideration from the time constant theory is that the farther the part geometry deviates from a simple lump of uniform material (and the more thermally resistive it becomes), the less constant the “time constant” is going to be.įor a rigorous approach, all sensor outputs should be converted to temperature before calculating the time constant. Even though most temperature sensors do not experience an instantaneous step change in temperature during actual use, the time constant is useful for comparing the relative performance of different sensor types or analyzing variation within a production batch. Often engineers test this step change by rapidly inserting a sensor at room temperature into heated water or oil. Sensor response time is an important performance parameter that is usually obtained by test measurements. Response time is described in terms of a time constant - which is the time necessary for a temperature sensor to respond to a 63.2% step change in temperature. That is, how quickly a temperature sensor measures change in temperature. For help in selecting the best configuration, contact Minco today.An important performance characteristic of temperature sensors is response time. It also offers the lowest cost of ownership and the added benefit of absolute protection from overheating.Įach of these three options offers different advantages depending on the project. On the plus side, it is the most compact and easy to install of the three configurations. SmartHeat is the least accurate and consistent of the three configurations, and has its temperature set point “baked in” at manufacturing. As the heater approaches its setpoint, the silicone layer’s resistance automatically increases, regulating the power to the element to maintain the setpoint. SmartHeat heaters use a patented silicone layer to automatically regulate temperature. Minco’s SmartHeat SLT™ line of self-limiting heaters take that simplicity to a new level, combining all three functions into a single component. They are also easier to assemble and take up less space. Two-component Heaterstat systems are somewhat less accurate and consistent than three-component systems, but they typically cost less. When resistance indicates that target temperature has been reached, the separate controller shuts down heating power but keeps checking resistance until it indicates that heating should resume. In operation the system briefly shuts down power to the heater and tests its resistance. Heaterstat systems sense temperature with a heating element whose resistance varies with temperature. Their downside is that they typically cost the most, take up more space, and require the most assembly.įor those applications requiring a more simplified setup, Minco’s Heaterstat™ product line combines the heater and sensor into one unit but still has a separate controller. This type of system is the most accurate and consistent and offers the most flexibility in choosing components. It reads two different temperature sensors and controls heaters with both solid-state and mechanical relays, offers PID and on-off heater control, and features a convenient Windows interface for configuring. Minco’s CT425 controller finds a place in many such assemblies. The classic three-component system consists of separate sensing, control, and heating components. Minco offers a variety of options for heater control. PID systems can be, in this sense, forward looking, and their tuning determines what factors besides temperature feedback from the sensor to consider in making decisions. Even the simplest home thermostat has an adjustable delay function that controls how quickly the thermostat and the system it controls can switch on and off. PID control systems-the term stands for proportional, integral, derivative-are designed to smooth out the operation of an on-off system and prevent “porpoising,” the jerky up-and-down operation that would occur if the system had only the binary options of on or off. ![]() At the other end of the sophistication spectrum are multi-zone model-based controllers that learn, using algorithms to analyze heat requirements by location, time, and use patterns and control heating accordingly. The most basic type of control operation is on-off switching like that of a traditional home thermostat. A typical heating design has three functions: sensing to indicate temperature, control to issue commands based on that information, and heating to carry out the controller’s directions. That’s why heating applications need controllers. ![]() Things catch fire, plane wings ice up, and biological tests give wrong results. Heating can be critical in many processes, but when it’s not properly controlled the results can range from inconvenient to catastrophic. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |