Difference between revisions of "Template:Coldjunctioncomp"

From Phidgets Support
Jump to: navigation, search
(Created page with "===Cold Junction Compensation and Self-heating=== Thermocouples consist of two junctions, one where the thermocouple meets the Phidget and one where the two wires are welded t...")
 
(Edited for eloquence)
Line 1: Line 1:
 
===Cold Junction Compensation and Self-heating===
 
===Cold Junction Compensation and Self-heating===
Thermocouples consist of two junctions, one where the thermocouple meets the Phidget and one where the two wires are welded together at the sensing end of the device.  In order to get accurate readings from the thermocouple one of these temperatures must be a known quantityIt doesn't make much sense to know the temperature at the end you are trying to sense at!  Therefore it stands to reason that we need to know the temperature at the end where the thermocouple connects to the Phidget.  This is why there is an ambient temperature sensor built onto the board.
+
Thermocouples consist of two junctions, one where the thermocouple meets the Phidget and one where the two wires are welded together at the sensing end of the device.  In simplified terms, a thermocouple works by detecting the temperature difference between these two junctionsAs such, in order to measure the temperature at the sensing end we need to know the temperature where the thermocouple connects to the Phidget.  This is why there is an ambient temperature sensor built onto the board.
  
An important thing to note though is that the ambient temp sensor measures the temperature of the air around the board and not specifically the junction.  Generally you can assume they are nearly one and the same value, however as the electronics get hot due to being powered up there can be some small error introduced.  This is exacerbated by having the board in an enclosed space where normal airflow is restricted thereby increasing the effect of self-heating.  As a result we recommend that the board be left in as open and well ventilated/cooled a place as possible to minimize this error source.
+
An important thing to note is that the ambient temperature sensor measures the temperature of the board and the air around it, though not specifically at the junction.  Generally you can assume they are nearly the same temperature, however as the electronics heat up by being powered on there can be some small error introduced.  This is exacerbated by having the board in an enclosed space where normal airflow is restricted thereby increasing the effect of self-heating.  As a result we recommend that the board be left in as open and well ventilated/cooled a place as possible to minimize this error source.

Revision as of 16:26, 6 June 2017

Cold Junction Compensation and Self-heating

Thermocouples consist of two junctions, one where the thermocouple meets the Phidget and one where the two wires are welded together at the sensing end of the device. In simplified terms, a thermocouple works by detecting the temperature difference between these two junctions. As such, in order to measure the temperature at the sensing end we need to know the temperature where the thermocouple connects to the Phidget. This is why there is an ambient temperature sensor built onto the board.

An important thing to note is that the ambient temperature sensor measures the temperature of the board and the air around it, though not specifically at the junction. Generally you can assume they are nearly the same temperature, however as the electronics heat up by being powered on there can be some small error introduced. This is exacerbated by having the board in an enclosed space where normal airflow is restricted thereby increasing the effect of self-heating. As a result we recommend that the board be left in as open and well ventilated/cooled a place as possible to minimize this error source.