How Resistance Temperature Device Works

Intlead Reply 1:27 PM
By Tracie Knight


Temperature is measured using different methods depending on the environment. RTD or Resistance temperature device is based on the scientific fact that changing the temperature of a conductor will affect its resistance. The flow of electric current as a result of heating or cooling is used in calibrating the devices. The principle of correlation is used with a great deal of standardization.

Platinum tops the list of metals used as conductors. It is favored by its consistency despite a wide range of change in temperature. This enhances its accuracy and reliability as a conductor to be used in monitoring temperatures during industrial processes. Its sensitivity to changing levels of heat gives it an edge over other conductors.

Industrial processes are very specific when dealing with heat. This raises the need for high sensitivity and faster response. The metals used in this case are carefully selected to ensure that their response time is minimized. It gives a signal to control and monitoring units to take action before the outcome is compromised.

Some of the sectors using this technology include automotive, HVAC, control sections and manufacturers of electronic appliances. It also is installed in testing and measuring units for production plants that need to monitor temperatures. The conductor used must be highly sensitive to achieve reliable levels of accuracy. Other metals used as conductors include nickel and copper.

The range of heat is important in determining the element to be used. Different industrial processes depend on the ranges to determine the products being extracted. It means that the element in use must not be distorted by high temperatures or be made to malfunction through freezing.

Exposure to heat causes varying reactions which is considered a limitation when using RTDs. Temperatures beyond 660 degrees Celsius have been known to damage the conductor or cause it to misbehave. Too much heat causes impurities to contaminate the conductor. They come from the sheath and affect measurement given.

Conductors behave different when contaminated by impurities. The impurities alter temperature changes and the trend can be noted at 3 Kelvin or 270 degrees and below. This is attributed to the presence of few phonons. It makes the conductors less sensitive.

RTDs face the challenge of maintaining accuracy when making conversions for the purpose of calibration. There is a delicate relationship between temperature and resistance in conductors. The interference of other properties affects the outcome which could lead to erroneous results and compromise industrial processes.

Prolonged thermal exposure is likely to affect the properties of conductors used. There is a possibility of recording different measurements over a cycle of heat and cold. This behavior is referred to as hysteresis. It has been observed in different elements and threatens the use of RTDs in sensitive and long running industrial processes.

The sheath also has the potential of conducting heat away from the process and thus affecting the outcome. Current being passed across the conductor may also come from other avenues. This is likely to affect the outcome. The number of wires used in the connection is likely to affect the results. Response time for the conductors is another challenge.




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