What is Thermocouple?
Thermocouple
is an electrical device which is used to measure the temperature. It
consists of electrical conductors which forms electrical junction at a different
temperature. These two electrical conductors are different from each other.
Thermocouple produces a temperature voltage as a result of thermoelectric
effect. This voltage can be taken to measure temperature. Thermocouple is also used
for temperature sensor.
Thermocouple Ammeter
Thermocouple Ammeter
is made up of two different size metals. The hot junction of the
thermocouple is welded to the heater wire and both are kept in a vacuum.
The cold junction of the thermocouple is connected to the moving coil
of the ammeter.
Thermocouple Diagram
Construction and Working
When the current is passed through the heater
wire and heat is generated in it and raises the temperature of the thermocouple
junction. The thermoelectric EMF increases and passes through the
moving coil of ammeter. The amount of the deflection on the moving coil
ammeter depends upon heating effect of the thermocouple. If the
amount of heat produced is directly proportional to the current then the scale
of ammeter is non-linear and is fit to work with both AC and DC.
Application of Thermocouple
It is also used for measuring radio
frequency currents which occurs in antenna and in transmitters.
It works accurately with DC and also measures high frequencies.