Change Currency

Thermocouples ANSI

Mineral Insulated or Fabricated thermocouples, as well as exposed junction thermocouples, in various sizes all in ANSI colours.

Comparison of Sensor Types

 

 

Thermocouple

Platinum Resistance Thermometer

Thermistor

Sensor

Thermoelement,

two dissimilar metals/alloys

 

Platinum-wire wound or flat-film resistor

Ceramic

(metal oxides)

Accuracy (typical values)

0.5 to 5.0°C

0.1 to 1.0°C

0.1 to 1.5°C

Long term Stability

Variable, Prone to ageing

Excellent

Good

Temperature range

-200 to1750°C

-200 to 650°C

-100 to 300°C

Thermal response

Sheathed – slow Exposed tip – fast 0.1 to 10 secs typical

Wirewound – slow

Film – faster 1-50 secs typical

generally fast 0.05 to 2.5 secs typical

Excitation

None

Constant current required

None

Characteristic

Thermovoltage

PTC resistance

NTC resistance (some are PTC)

Linearity

Most types non-linear

Fairly linear

Exponential

Lead resistance effect

Short cable runs satisfactory

3 & 4 wire – low.       2 wire – high

Low

Electrical “pick-up”

susceptible

Rarely susceptible

Not susceptible

Interface

Potentiometric input. Cold junction compensation required

Bridge

2,3 or 4 wire

2 wire resistance

Vibration effects/ shock

Mineral insulated types suitable

wirewound – not suitable. Film – good

Suitable

Output/ characteristic

From 10µV/°C to

to 40µV/°C depending on type

approx. 0.4 W/°C

-4% / °C

Extension Leads

Compensating cable

Copper

Copper

Cost

Relatively
low cost

Wirewound – more expensive

Film – cheaper

Inexpensive
to moderate

 

Comments and values shown in this chart are generalised and nominal. They are not intended to be definitive but are stated for general guidance.