Thermocouple Data Acquisition from MCC
Thermocouples, also called thermal junctions, thermoelectric thermometers, or thermal, are temperature-measuring devices consisting of two wires of different metals joined at each end. One thermocouple junction is placed where the temperature is to be measured, and the other is kept at a constant lower temperature. A measuring instrument is connected in the circuit. The temperature difference causes the development of an electromotive force (known as the Seebeck effect).
How they work
Discovered by accident in 1822 by an Estonian physician named Thomas Seebeck, the term thermocouple originates from the junction between two metals generating a voltage, which is a function of temperature. This is also known as Seebeck effect. Although almost any two types of metal can be used to make a thermocouple, a number of standard types are used because they possess predictable output voltages and large temperature gradients.
A voltage is produced by the junction at any given temperature. For example, the K type thermocouple at 300°C will produce 12.2mV. This amount is not measurable by a voltmeter, because the connection of the voltmeter leads will make a second, undesired thermocouple junction.
To accurately measure this voltage, we must compensate for using any contact made to a thermocouple -- a technique called cold junction compensation (CJC).
It is important to keep this in mind when we construct thermocouple junctions. Based on this law, it is quite acceptable to make a junction by soldering the two metals together as the solder will not affect the reading. In practice junctions are made by welding the two metals together (usually by capacitive discharge) because this ensures that the performance is not limited by the melting point of solder.
Features
- 8 thermocouple input channels
- Supports J, K, R, S, T, N, E, & B type TCs
- Built-in ambient temperature sensor
- 8 digital I/O bits
General Description
The Advantage of easy temperature measurement! The USB-TC provides 8 inputs and supports all of the common thermocouples. The USB-TC performs all linearization and cold-junction compensation and returns data in degrees C or F.
Powerful, accurate, great value: The internal measurement electronics accuracy exceeds the accuracy specifications of the temperature sensors so you are guaranteed to record the most accurate data possible. Unlike NI who advertises the internal resolution of the A/D converter, MCC guarantees you that the USB-TC will provide the best measurement your sensor is capable of. The USB-TC is the best value in temperature measurement at only $37 per channel!
Thermocouple Boards
Thermocouple USB
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