A temperature sensor is a device that detects and measures hotness and coolness and converts
it into an electrical signal.
There are different types of temperature sensors, that have sensing capacity depending upon
their range of application.
The six basic types of temperature measuring sensors discussed in this video.
There are thermocouples, RTD, Thermistors, Semiconductor sensors, Infrared Temperature
Sensors, Thermometers.
Thermocouples:- A thermocouple is an electrical device consisting
of two dissimilar electrical conductors forming electrical junctions at differing temperatures.
A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric
effect, and this voltage can be interpreted to measure temperature.
Thermocouples are used in many industrial, scientific, Power Generation, Oil or Gas,
Pharmaceutical, Biotech, Cement, Paper & Pulp, etc.
Thermistors:- A thermistor is a type of resistor whose resistance
is dependent on temperature, more so than in standard resistors.
Thermistors are of two opposite fundamental types:
1.
Negative temperature coefficient or NTC type thermistors, resistance decreases as temperature
rises.
An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current
limiter.
2.
Positive temperature coefficient or PTC type thermistors, resistance increases as temperature
rises.
PTC thermistors are commonly installed in series with a circuit, and used to protect
against overcurrent conditions, as resettable fuses.
Resistor Temperature Detectors:- Resistance temperature detectors (RTDs) differ
from Thermistors in that the material used in a thermistor is generally a ceramic or
polymer, while RTDs use pure metals.
The thermistors are in the form of beads, rods and discs but RTDs are in different shapes
and sizes.
The temperature response is also different; RTDs are useful over larger temperature ranges,
while thermistors typically achieve a greater precision within a limited temperature range,
typically -90 �C to 130 �C.
Semiconductor Sensors:- They are classified into different types like
Voltage output, Current output, Digital output, Resistance output silicon and Diode temperature
sensors.
Modern semiconductor temperature sensors offer high accuracy and high linearity over an operating
range of about 55�C to +150�C. Internal amplifiers can scale the output to convenient
values, such as 10 mili Volts/�C. They are also useful in cold-junction compensation
circuits for wide temperature range thermocouples.
Infrared Temperature Sensors:- Infrared Temperature sensors are non-contacting
sensors.
As an example, if you hold up a typical infrared sensor to the front of your desk without contact,
the sensor will tell you the temperature of the desk by virtue of its radiation - probably
68�F at normal room temperature.
In a non-contacting measurement of ice water, it will measure slightly under 0�C because
of evaporation, which slightly lowers the expected temperature reading.
Thermometers:- A thermometer is a device that measures temperature
or a temperature gradient.
A thermometer has two important elements: 1.
a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer). in which some change occurs
with a change in temperature. and 2.
some means of converting this change into a numerical value (e.g. the visible scale
that is marked on a mercury-in-glass thermometer).
Thermometers are widely used in technology and industry to monitor processes, in meteorology,
in medicine, and in scientific research.
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