Temperature Monitoring System: Types of Control
At least one temperature monitoring system can be found in every home. This hard working yet vastly unappreciated device is what allows your refrigerator and freezer to keep your meat frozen, your produce fresh and cool, and your dairy products from going bad. It is what tells your oven to heat when you set it to 350 degrees so that you can bake that cake for your sister’s birthday. And it is what tells your thermostat to turn on the AC when it’s 100 degrees outside and you’d like your home to be 72 degrees. There are a few different ways in which this amazing system works; different control mechanisms cause the temperature adjustments in unique ways. Here are some of the ways through which a temperature monitoring system can function.
First, How Does It Generally Work?
To maintain the temperature, a temperature monitoring system uses an instrument to measure the current temperature of the device and compares it to what the set temperature is. After finding the difference between them (called the “error”), it calculates the time it should take to adjust the temperature and then signals the final control element to heat or cool as needed. It also takes into account factors such as ambient temperature and air circulation, humidity, and of course the size of the device to be heated or cooled.
Types of Control
On-Off control uses negative feedback and is fairly straightforward. For some systems, if the temperature is measured at going below the set temperature, the heat is turned on. Likewise, for other systems, if the temperature is measured at having gone above the set temperature, cooling will turn on. A good example of this is a thermostat or a refrigerator. It operates like a switch that is flipped ON or OFF to adjust the temperature.
Linear control functions in a linear way, also with negative feedback, creating a mathematically based control signal to regulate the temperature within a range. Thus, it may actually power the actuator on and then off again multiple times to adjust the temperature. A subcategory of linear control is proportional control, in which usually only small changes in temperature are effected at a time because the temperature monitoring system is acting in proportion to the settings for the device. For example, high powered industrial furnaces usually use proportion control so as to protect against thermal shocks and to balance the heat carefully. Unlike on-off control, which usually overshoots the desired temperature, proportional control is more careful about using shorter, smaller increments of time to reach the set temperature without overshooting it.
PID control uses proportional control as well as two other elements, derivative and integral. The derivative function affects the error’s rate of change, speeding up or slowing down to reach the set temperature. The integral function steadies the error to reduce its vacillation. This combination produces the most precise temperature monitoring system control of the above types and is best suited to smaller devices due to its quick reaction to temperature and energy changes.
Fuzzy logic control is another type, which uses a supposedly human-like thought process to try to judge the error and add more heat or less heat in accordance with its estimation. The input is highly varied, but the output is usually smooth and controlled; it can work with nonlinear systems that cannot be mathematically computed by the other forms of control.
Through one of these control processes, each temperature monitoring system in your home maintains your home automation system’s functionability. Thankfully, we can rely on them to do the thinking and monitoring for us so that we can utilize the home automation products they maintain while continuing about our daily lives.