Temperature

TC Type J

RTD

Temperature is a measure of the thermal energy of a substance. It indicates how hot or cold a substance is and is measured in degrees. The most commonly used temperature scales in industrial automation are Celsius (°C), Fahrenheit (°F), and Kelvin (K).

Basic Temperature Conversion Formulas

Temperature can be converted between different scales using the following formulas:

• Celsius to Fahrenheit: °F = (°C × 9/5) + 32
• Fahrenheit to Celsius: °C = (°F - 32) × 5/9
• Celsius to Kelvin: K = °C + 273.15
• Kelvin to Celsius: °C = K - 273.15
• Fahrenheit to Kelvin: K = (°F + 459.67) × 5/9
• Kelvin to Fahrenheit: °F = (K × 9/5) - 459.67

Temperature plays a crucial role in various applications. Here are some common calculations and conversions:

Temperature Monitoring

Accurate temperature monitoring is essential for ensuring the safety and efficiency of industrial processes. Sensors such as thermocouples, RTDs (Resistance Temperature Detectors), and thermistors are commonly used for temperature measurement.

Example calculation for temperature monitoring:

• Task: Convert a temperature reading of 150°C to Fahrenheit.
• Solution: Use the conversion formula: °F = (°C × 9/5) + 32.
• °F = (150°C × 9/5) + 32 = 302°F

Temperature Control

Temperature control is vital for maintaining the desired temperature in industrial processes. Controllers such as PID (Proportional-Integral-Derivative) controllers are used to regulate temperature within set limits.

Example calculation for temperature control:

• Task: Set the temperature of a process to 450°F. Convert this temperature to Celsius for the controller.
• Solution: Use the conversion formula: °C = (°F - 32) × 5/9.
• °C = (450°F - 32) × 5/9 ≈ 232.22°C

Temperature Compensation

Temperature compensation is used to adjust readings of instruments and sensors for changes in temperature. This ensures accurate measurements under varying temperature conditions.

Example calculation for temperature compensation:

• Task: Compensate a sensor reading of 60°C when the actual temperature is 65°C.
• Solution: Adjust the sensor reading by the difference: 65°C - 60°C = 5°C.
• The compensated reading is: 60°C + 5°C = 65°C

Average Temperature Calculation

Calculating the average temperature over a period can help in analyzing trends and making informed decisions.

Example calculation for average temperature:

• Task: Calculate the average temperature from the following readings: 25°C, 27°C, 29°C, 26°C, and 28°C.
• Solution: Use the average formula: Average = (Sum of Temperature Readings) / (Number of Readings).
• Average = (25 + 27 + 29 + 26 + 28) / 5 = 27°C

Type J Thermocouple Voltage vs. Temperature Chart

Temperature (°C)	Temperature (°F)	Voltage (mV)
-210	-346	-8.095
-200	-328	-7.988
-150	-238	-6.276
-100	-148	-4.553
-50	-58.0	-2.819
0	32.0	0.000
50	122.0	2.748
100	212.0	5.459
150	302.0	8.150
200	392.0	10.821
250	482.0	13.471
300	572.0	16.100
350	662.0	18.709
400	752.0	21.298
450	842.0	23.867
500	932.0	26.416
550	1022.0	28.946
600	1112.0	31.455

RTD (Resistance Temperature Detector) Voltage vs. Temperature Chart

Temperature (°C)	Temperature (°F)	Voltage (mV)
-200	-328	0.570
-100	-148	0.765
0	32.0	1.000
100	212.0	1.329
200	392.0	1.676
300	572.0	2.060
400	752.0	2.491
500	932.0	2.984
600	1112.0	3.556
700	1292.0	4.229
800	1472.0	5.036
900	1652.0	6.020
1000	1832.0	7.239