TRANSDUCERTemperature Measuring

Transducer

INTRODUCTION:

oThe transformation of vitality starting with one frame then onto the next is known as Transduction. A transducer fills for this need.

oA transducer is a device which converts signals from one form to another. This can include loudspeakers and linear positioners are well as physical quantity to electrical signal devices. The latter are most frequently referred to as sensors. They allow computers and other electronic devices measure, operate and control things.

oWe can state that Every transducer is likewise (or has) a sensor yet every sensor requires not be a transducer.

TYPES OF TRANSDUCER:

1. Ultrasonic Transducer : Convert ultrasonic waves to equivalent electrical signals or vice versa. 2. Temperature Transducer Convert temperature into equivalent voltage or their internal resistance varies with temperature. 3. Piezoelectric Transducer convert the electrical charges produced by some forms of solid materials into energy.4. Pressure Transducer Converts pressure into an analog electrical signal.

TEMPERATURE MEASURING TRANSDUCER:

These are some basic types of Transducer used for the measurement of temperature. 1. Thermocouples 2. Thermistor 3. Resistance Thermometers 4. Integrated Circuit Temperature Transducers

THERMOCOUPLES:

oA thermocouple is a pair of dissimilar metals that will generate a small potential voltage that is linearly dependent on temperature. The voltage per degree is a function of the two metals.

oUsually they are made as sensors using two dissimilar wires with the junction being the sensing point. An amplifier and a reference junction at (often freezing) or some reproducible point is required to complete the circuit. Often the reference junction can be electronic.

THERMOCOUPLES-WORKING PRINCIPLE:

oA thermocouple is a device that measures temperature by the means of EMF generated between hot and cold junctions. The device works on the principle of Peltier's effect and Seebeck effect.

oTo measure temperature through a thermocouple what you need is a hot and a cold junction connected by wires and a transducer with display unit.

oThe Peltier's effect states that an EMF is induced or a potential difference exists in the loop if a temperature difference is maintained at two points in the loop.

oWhile the Seebeck, effect implies that thermoelectric current is produced in a wire if a Temperature-Difference is introduced at the both ends of the wire.

THERMOCOUPLES-BASIC CONSTRUCTION:

Thermocouple's are amassed with two unique metal wires joined toward one side. Thermocouples might be produced of a few unique mixes of materials. The execution of a thermocouple material is for the most part controlled by utilizing that material with platinum. The most imperative element to be considered while selecting a couple of materials is the "thermoelectric distinction" between the two materials. A noteworthy distinction between the two materials will bring about better thermocouple execution.

THERMOCOUPLES-APPLICATIONS:

Sort K (chromel/alumel) Thermocouples are accessible in the –200 °C to +1200 °C extend.Sort “E” (chromel /constantan) They process a huge yield (68 µV/°C) which makes it appropriate to low temperature utilize. Sort J (press/constantan) Constrained range (–40 to +750 °C) makes sort J less prominent than sort K. The primary application is with old gear that cannot acknowledge "advanced" thermocouples. Sort N (nicrosil/nisil) High solidness and imperviousness to high-temperature oxidation makes sort N reasonable for high temperature estimations without the cost of platinum (B,R,S) sorts.

THERMISTORS:

oThermistors are semiconductor resistance thermometer used to measure the temperature. These are made of semiconductor compounds such as sulphides, oxides, silicates of Mn, Co, Ni, Fe etc.

oThese are of different shape like Bead, Disc, Rod. These are used for temperature range of 200 to 3000C.

THERMISTORS-WORKING PRINCIPLE:

Working principle of thermistor is very simple as shown below:o It is shown be the below equations, Resistance is

R = Ro ekK = β(1/T – 1/To)

o In the above equation, R is the resistance of the thermistor o In the above equation, Ro represent the Thermistors- Resistance at a specific T. oNaperian-logarithms is represented by e o Constant factor in the equation is represented by beta.

THERMISTORS-BASIC CONSTRUCTION:

These contraptions are produced using materials like sintered mixes of oxides of metals, for instance, manganese, nickel, cobalt, and iron. Their resistances go from 0.4 ohms to 75 super ohms and they may be made in wide grouping of shapes and sizes. Tinier thermistors are as touches of width from 0.15 millimeters to 1.5 millimeters.

THERMISTORS-APPLICATIONS:

oMicrowave Used in machines having microwaves system.oCircuit Protector Used as the circuit Protector.oAutomotive Used in Automotive parts.oDigital Thermometers Used in digital thermometers.oRechargeable Batteries Thermistors are used in Rechargeable batteries.

RESISTANCE THERMOMETERS:

oResistance-Temperature-Detector is a uninvolved circuit segment whose resistance increases with growing temperature in an expected way.

oThe traditional R.T.D part is worked of a little circle of platinum, copper, or nickel wire, turned to a correct resistance regard around a pottery or glass bobbin. The twisting is all around done using this; birdcage or helix. The birdcage winding keeps the platinum wire openly wound on the bobbin allowing it to augment and contract energetically over temperature with a particular true objective to minimize any nervousness incited change in resistance

RTD-WORKING PRINCIPLE:

The Resistance temperature detector is a temperature sensor that chips away at the estimation decide that a material's electrical resistance varies with the variation with temperature. The relationship between a R.T.D's resistance and the including temperature is exceedingly obvious, considering definite and unsurprising temperature estimation.

RTD-BASIC CONSTRUCTION:

The advancement is regularly to such a degree, to the point that the wire is bent on a shape on indented mica cross edge to achieve minimal size, improving the warm conductivity to decrease the response time and a high rate of warmth trade is gotten. In the mechanical Resistance temperature detector's, the circle is secured by a stainless-steel sheath or a cautious tube.

RTD-APPLICATIONS:

o Resistance thermistors are used in HVAC System. Air-Conditioning-&-Refrigeration systems

o Resistance thermistors are used in the processing of different types of Foods.o Resistance thermistors are used in different types of Stoves as well as in grills.o Resistance thermistors are used in productions of different kind of textile.o Resistance thermistors are used in the processing of Plastics.o Resistance thermistors are used in the processing of Petrochemical.o Resistance thermistors are used in huge applications related to Microelectronics.o Resistance thermistors are used for the measurements of Air, gas and liquid

temperature.

ICT-TRANSDUCERS:

These are the temperature transducers which utilize the temperature detecting component with solid electronic circuits as a mix for the estimation of temperature.

ICT-TRANSDUCERS WORKING PRINCIPLE:

IC sensor more often than not have a temperature measuring equipment, a two-wire advanced interface and registers for controlling the IC's operation. Temperature is persistently measured and can be perused whenever. On the off chance that craved, the host processor can train the sensor to screen temperature and take a yield stick high (or low) if temperature surpasses a modified point of confinement. Bring down edge temperature can likewise be modified and the host can be informed when temperature has dropped underneath this edge. Consequently, computerized yield sensor can be utilized for solid temperature checking as a part of microchip based frameworks.

ICT-TRANSDUCERS BASIC CONSTRUCTION:

The temperature sensor made up of silicon is a coordinated circuit, and can in this way incorporate broad flag handling hardware inside an indistinguishable bundle from the sensor. There is no compelling reason to include remuneration circuits for the sensing equipment used for temperature is Integrated Circuit system. Others consolidate simple detecting circuits with voltage comparators to give ready capacities. Some other sensor ICs consolidate simple detecting hardware with advanced information/yield and control registers, making them a perfect answer for chip based frameworks.

ICT-TRANSDUCERS APPLICATIONS:

o Integrated circuit temperature transducer has huge applications in the different kinds of circuit sheets which are used to screen and control temperature.

o Integrated circuit temperature transducer has some applications in PCs to control Central Power Unit temperature, related to part of a computer.

o Integrated circuit temperature transducer is used in media communications applications.

o Integrated circuit temperature transducer has some applications in mechanical submersion uses.

COMPARISON:

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