# Comparison between temperature measuring devices

**URL:** <https://forumautomation.com/t/comparison-between-temperature-measuring-devices/3390>\
**Category:** Temperature Measurement\
**Tags:** instrumentation\
**Created:** [April 9, 2018, 11:48am UTC](https://forumautomation.com/t/comparison-between-temperature-measuring-devices/3390 "2018-04-09T11:48:53Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sivaranjith](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@sivaranjith](https://forumautomation.com/u/sivaranjith)\
**Post date:** [April 9, 2018, 11:48am UTC](https://forumautomation.com/t/comparison-between-temperature-measuring-devices/3390/1 "2018-04-09T11:48:55Z")

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The four most common temperature transducers are thermocouples, resistance-temperature detector’s (RTD’s), thermistors, and integrated circuit sensors.

Here we are discussing about advantages and disadvantages of each devices

> ## Thermocouple:

A[**thermocouple**](https://automationforum.co/2018/02/thermocouple-basics-types-thermocouple.html) is an active transducer which directly converts thermal energy into electrical energy. It is a simple device made by joining to dissimilar metals or semiconductor forming a junction. It produces a voltage when the temperature at the junction changes. Have a temperature range in different types -300 to 3200°F

**Chara & symbol:**![](https://cdn.forumautomation.com/original/2X/f/f3b52130dc6798f6fdf0292c511861adeea08ffa.png)

**Advantages:**

- Self-powered
- Simple
- Rugged
- Inexpensive
- Wide variety of physical forms
- Wide temperature range

**Disadvantages:**

- Non-linear
- Low voltage
- Reference required
- Least stable
- Least sensitive
- Complicated conversion from emf to temperature

> ## RTD:

[**RTD**](https://automationforum.co/2018/02/resistance-temperature-detector-rtd.html) (Resistance Temperature Detectors) uses metals that change their resistance when exposed to temperature, which has a positive temperature coefficient. For PT100 RTD it has a temperature range from -400 to 1200F.

**Chara & symbol:**

 ![](https://cdn.forumautomation.com/original/2X/7/777447d62f340abd0ab1eadc9c93a4ea3577aeb6.png)

**Advantages:**

- Most stable
- Most accurate
- More linear than thermocouple.
- Interchangeability over wide range
- Works in wide temperature ranges

**Disadvantages:**

- Bulky in size and fragile
- Expensive
- Slow
- Current source required
- Small resistance change
- Four-wire measurement
- Self-heating problems

> ## Thermistor:

[**Thermistors**](https://automationforum.co/2018/02/basics-of-thermistor-advantages-and-disadvantages.html) are semiconductor devices which have a negative temperature coefficient, this means that the resistance decreases with an increase in temperature.

Thermistors are available that perform temperature measurement from -73 to 316°C (-100 to 600°F). It should be noted that many have limited ranges and cannot be used above 120°C (250°F).

**Chara & symbol:**

 ![](https://cdn.forumautomation.com/original/2X/d/d66bf31be042171036066fb1b6c36814f5be8ec3.png)

**Advantages:**

- High output
- Fast
- Two-wire ohmic measurement
- Very high sensitivity (Select range)
- Inexpensive
- No cold junction compensation

**Disadvantages:**

- Not easily interchangeable
- Limited temperature range
- Fragile
- Current source required
- Self-heating
- Narrow span
- Unstable due to drift and decalibration (especially at high temperatures)

> ## I.C sensor:

They are semiconductor devices. These are available in both voltage and current-output configurations, Some integrated sensors even represent temperature in a digital output format that can be read directly by a microprocessor.

**Chara & symbol:**

 ![](https://cdn.forumautomation.com/original/2X/4/435b6a7516017251c04e3d476b04d8aa4d0b01b5.png)

**Advantages:**

- Most linear
- Highest output
- Inexpensive

**Disadvantages:**

- T \< 250°C
- Power supply required
- Self-heating
- Limited configurations