According to the budget to choose what kind of precision thermocouple temperature measurement

Acceptable precision measuring instruments in the temperature problem is no longer the price today. But when measuring who do not pay attention to brand all the accuracy of the offset.

in October 2001, who would like to precise measurement temperature was the most expensive and temperature sensors and measuring instruments to buy the most advanced technology will take the budget. But, in order to get the best measurement results as a result, not necessarily. Before any decision is taken to sensors and instruments type has three basic aspects: & bull; Measuring temperature is what is what? Around the room temperature is accurate to 1 & deg; C？ Is not so easy, because the room temperature is not unified. It's different with height in the room.

it in the temperature of the sensor records only. In order to measure a hot water pipe temperature sensor is not really the temperature of the water - Pipe between the medial and lateral, there is a temperature gradient. Ambient air temperature and air flow around the surrounding temperature sensor augmented error measurement. Finally, temperature sensor, the influence of the measurement itself: but he and by its own heat measurement point measuring current. Obviously,

what to measure, it is decide which type of temperature sensor in accordance with this. Three of the most common in the research and industrial use of sensor is the thermocouple, RTD and thermal resistor. Thermocouple precision probe the - 2° C is a typical - error But they have a wide temperature range for - 200 ℃ to 2000 ℃, and often need, because the other sensors at desired temperature doesn't work. They are also relatively low prices, wide range of USES. A - because of the thermocouple Although a small voltage - Their own production, they need to use any external excitation current for them. However, this is not a simple voltmeter connected to the thermocouple in the voltage is measured, because the first two, two different transition metal forming out of control, and so the other two thermocouples. So use is called & other; Cold junction compensation & throughout; The technology is invoked. All standard thermocouples table considering the second mouth, by assuming that the right be kept under 0 ℃. It is a common reference end temperature through the thermistor can dig precision, good contact with the measuring instrument at the input heat. Instrument from the calculation and from the thermocouple readings along the true temperature sensor of the thermocouple temperature readings. Any error in the measurement of the temperature of the cold end, therefore, will be fully into the main measurement.

element has a high resistance. This can be caused by the limited input resistance measuring instrument error. Usually 32 awg wire with 0. 25 mm diameter of about 15 ohmic resistance per meter. If you use a long thin thermocouple wire or cable, then connect the thermocouple wire as short as possible and even used for thermocouple measuring instrument is a thermocouple extension cord is used. This is much thicker than the sensor line, so has low resistance. However, it should be only type of match of the thermocouple used to extend, otherwise an extra, do not want the thermocouple junction. The same applies to plug, plug and terminal board, once again, because two of the same metal, such as thermocouple must exist and extension. Because thermocouples provide only microvolt signal interference problems can occur. In order to reduce this, transfer to the cable away from the interference sources, the distortion whether coming from thermocouple ( Isolation) Line, thus two cables to absorb the same error. People can also use shielding extension cord. The last question and thermocouple: they too much, if can cover a wide range of temperatures, can they change permanently ( In technical terms: Dekalibration) If it, or be in the range of working temperature extremum and even beyond the operation. The next is common temperature sensor resistance thermometer. It is the most stable and accurate, but costly and weak solution. The underlying physical effects: a resistance and high temperature metal increases. The most common resistance thermometer and made a practical temperature ranges from - platinum From 250 to 850 ℃. Resistance thermometer accuracy 0 type according to the program. 3 to 0. 3℃。 The most commonly used is called platinum 100 platinum sensor, because he has 100 ohm resistor under 0 ℃.