A thermocouple is a device which generates an electrical charge when
heated. It is often used on a boiler to indicate that the pilot light
is on and hot, so it should be safe to allow gas to pass to the main
burner for heating water, your house, etc. Should the pilot light go
out, the thermocouple will sort of "tell" the boiler to shut off the
gas, as it isn't safe to fire up.
A thermostat is used as a switch, which goes on and off at a certain
temperature. For example, in a boiler it will tell the boiler that the
water in the circuit is plenty hot enough and that it doesn't need to
be heated any more, in your house it will tell your central heating
that the room is warm enough and doesn't need heating any more and in
your car it would say that your engine is too hot and that the radiator
valve should open, and perhaps the cooling fan should turn on.
is a thermocouple an active or passive transducer?-why?
Yes, it's an active transducer. A thermocouple is passive not active
Thermocouple is a heat sensing device.It is made up of 2 dissimilar metals twisted/joined at one end called a junction and that is made Hot and the other end or tell end is cold (may be at 0 degree C). then a voltage is developed accross the two dissimilar metal, this principle is called SEEBECK EFFECT.The voltage developed is directly propersional to the difference in temperature.
The maximum sensed
A thermistor is a temperature measuring device which acts like a temperature sensitive resistor. It is an active device that requires a current flow to measure its resistance so that the temperature may be calculated and/or displayed. A thermocouple is a device composed of two dissimilar metals fused together. An electrical potential occurs across the junction of the metals. As the potential is influenced by the temperature of the metal junction the output voltage can be measured and calibrated to show the temperature at the joint. Both devices may be employed to measure the temperature within a fixed space, or on a probe to measure the temperature at a remote point or points.
you use a thermocouple instrument
A thermostat controls temperature, a thermometer measures it.
A humidistat senses humidity, thermostat temperature.
A thermocouple measures temperature difference between two points, producing a tiny voltage corresponding to the difference in temperature. To measure temperature with a thermocouple, you need to know the temperature of one junction and calculate the difference from the table or equation for the type of t/c used. An RTD changes resistance in response to temperature--to measure temperature with an RTD you measure its resistance (usually by putting a known voltage across it and measuring the current).
measuring temperature difference
Since a thermocouple responds to temperature, it can be used as a thermostat, to set a specific temperature for your electric frying pan.
The thermocouple does not actually measure temperature, but the temperature difference between two points. If the temperature at one point is known (reference junction) then the temperature of the other point (sensing junction) can be calculated.
You light the pilot. if it will not stay lit,the thermocouple is bad.
one is called a thermostat and the other is called a thermistor - Ross Henderson
If a Salamander Grill keeps going out and the thermocouple is okay and the valve is new then a faulty thermostat could be the cause. Replacing the thermostat or re-calibrating it generally solves the issue.
A thermocouple uses the thermoelectric effect to do what it does. Thermal energy (heat) is converted into a difference of potential, which is electric (electromagnetic) energy.
A thermostat is used to set the room to your desired temperature, whereas a thermometer just measures temperatures