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For a better understanding is necessary to present the basic configuration of the sensing element. At the end of the sensor lead wires are welded and insulated, and the assembly is inserted in a metallic tube. Since the resistance value that allows the determination of temperature is only the sensor resistance and not the resistance of the connecting wires, there are three basic schemes for sensor connection that circumvent the inevitable fact of having to use lead wires to measure the sensor resistance.
2-Wire Connection: (second left picture)
The Wheatstone bridge has a resistance thermometer with two wires connection. In the equilibrium condition of the bridge, which occurs when the galvanometer "G" indicates zero, one gets the following relationship between the resistance:
Rsensor + RL1 + RL2 = R1.R3 / R2
If R3 = R2 then Rsensor + RL1 + RL2 = R1. Since R1 is known, it is determined the value of Rsensor + RL1 + RL2.
Clearly, the value of sensor resistance values are increased resistance of the connecting wires, which decreases the quality of the measurement with the resulting error in temperature measurement.
3-Wire Connection: (third left picture)
In this case the bridge is connected to a three wires resistance thermometer. Considering again that R2 = R3, the balance of the bridge will result from the condition:
Rsensor + RL2 = R1 + RL1
How is it possible, with good approximation, consider approximately equal to RL1 RL2 RL3 approximately equal to, the effect of the wire is much attenuated.
This is the type of connection used in resistance thermometers for industrial applications.
4-Wire Connection: (on the right picture)
The four wire system connection completely eliminates the resistance of the connecting wires, being used in situations that require very precise measurements. PRT elements are manufactured with four wires connection.
This configuration is intended for use in laboratories, reading instruments of reference sensors allowing the circulation of a constant current (usually 1mA) through the sensor element and the potential difference measuring are made on the sensor terminals thus eliminating the effect of the resistance of the leads in the final result.
The easiest way of finding the right infrared thermometer for your application is during a commitment-free personal consultation with one of our team member, or using the
optris Pyrometer Selector
If you still prefer to keep looking for the right pyrometer yourself, you should start by determining the properties of the object surface on which your measurements are to be performed. A particularly important parameter in this respect is emissivity ε. The following wavelength ranges are available: 8-14 µm (non-metal surfaces), 5,0 µm (glass surfaces), 0,5 - 2,3 µm (metal) and 2,3 - 7,9 µm (special applications, as temperatures on films, combustion gases, temperatures through flames, laser applications)
The use of the right optics is indispensable in order to achieve precise measurement results. It depends on the size of the object to be measured and the distance between the object and the pyrometer. The easiest way of determining the right optics for your thermometer of choice is using the
measurement spot calculator for pyrometers
A data logger or datalogger is an electronic device that is used in conjunction with a computer to monitor or record various signals.
Remember when you were at school and you did experiments, measuring the temperature of boiling water, taking a reading every minute until it boiled. Well, a data logger would do this for you automatically. All you need to do is put the sensor in the water and tell the data logger how often to take a reading and at the end of the experiment, you download the information to the computer and it will produce a graph for you.
The data logger may have internal sensor(s) so it measures where it is located or it may have one or a number of channels where external sensors can be connected. Some data loggers can be configured to accept a wide range of sensors.
Using the computer, the data logger is programmed to "wake up" at predetermined intervals, take a reading and go back to sleep. The time period between readings is called the "sample period" and can range from many readings per second to once per day. The data logger will have an internal memory where the readings are stored. Once this memory is full, the data logger can be programmed to stop taking new readings, and therefore not loose any readings or, overwrite the oldest reading.
Once the data logger has been monitoring for the required time period, it is connected to the computer. The stored readings are then downloaded and saved on the computers hard disk. A graph can now be produced showing the measured signal over time - providing an accurate account of what the data logger measured - useful for proving a shipment got too hot in transit or that your office is too hot to work in!
Once the stored information has been downloaded from the data logger, the memory is cleared and the data logger is ready to be re-used over and over again - well, until the battery runs out, which is usually a number of years.
Data loggers are used in a wide variety of applications from simple monitoring of temperature in an office environment to monitoring the temperature of perishable products in transit or optimising the production process of food, pharmaceutical or engineering products. The same data logger can be used in a variety of applications, if you want to make a record of temperature, humidity, pressure or Voltage and current signals, we have a data logger to suit your needs.
Bellow is shown as an example, a typical graph that you would get from a Signatrol data logger. It was produced by the graphing software - TempIT, although some functions shown are only available in the PRO version:
An atmosphere is defined as potentially explosive when its composition is not explosive, but due to unexpected circumstances, could evolve into explosive (the danger exists in a potential state). These circumstances could be:
Metallic and organic products that create dust and powder on certain conditions can become active agents of an explosion. It presents an exclusive list of some of these products:
Email our Customer Support Team and we will get back to you in 1-2 business days.
Our team provide turn-key services that will help you select your perfect instrument for the measurement task, perfect integration in your system and facilities, using our standard or custom made products.
Portuguese company of process instrumention and manufacturer of temperature, pressure and level sensors and transmitters.
Parque Empresarial da Baía do Tejo Rua 48 N. 11, Apartado 5056
2830-571, Barreiro - Portugal
(+351) 212 070 802
(+351) 212 070 803