What is Resistance thermometer or resistance temperature detectors (RTDs)

Resistance thermometer or resistance temperature detectors (RTDs) is a temperature sensor to measure temperature by the property of changing resistance of the metal used in RTD's.

The RTD is made of pure metal,whose resistance change property with temperature is linear.Different resistance and corresponding temperature data is documented to use RTD as a thermometer.

Generally platinum is used as the metal in RTD's.

What is Thermistor and difference with RTD

Thermistor is a sensor to sense temperature.It is basically a resistor whose resistance varies with temperature.

Thermistor=Thermal+resistor -the naming of thermistor.

Difference between Thermistor and RTD:

• As construction material only ceramic or polymer is used in thermistor,where RTD is made of pure metal.
• As temperature response RTD's are useful over larger temperature range and thermistor for -93 to 130c.

What is Position Sensors

Reports the physical position of  an object from a reference point to the control system.
Position might be -

• Angle - in degree.
• Linear distance-inch,cm

What is Sensor or transducer

Sensor sense from a system and informs it to the control system.Sensor may converth the signal so that the control system can understand this.

Sensor may sense

• Electrical parameter.-Current,voltage
• Mechanical parameter-heat,light,speed,distance.