The source of the thermocouple _ instrument

Thermocouple temperature measurement factors influencing the precision of a lot of, have the original error, the error of the error and design on the signal transmission, such as metal formed by a group of atoms arranged according to certain rules, each atom has a layer of ( Or multilayer) Composed of electron shell. In the shell of electrons can flow out of the attraction of the nucleus and everywhere, is a major cause of metals can conduct electricity. When the metal produce electric potential difference on both ends ( The voltage) , the electrons due to the influence of electric field and the flow of the rules, for the current. In reality, the material of atomic arrangement would not make rules completely, so the electron flow will be arranged according to the rules of atom not break up on the way, is the source of the resistance. After doped semiconductor due to upset the original atomic arrangement, thus causes the resistivity to rise. In the process of electron flow, there will be a small part of the electron impact to other atoms, off course, part of the energy loss due to the impact will be at this moment, into internal energy. This is the wire on the energy loss due to the resistivity, so people always want to reduce the resistivity of the wire. Thermocouple is pt100 platinum thermocouple, it can be temperature measuring instruments which are frequently used in low temperature range, its use range is very wide, across the medical, electric meter, industrial production, temperature instruments and other high precision temperature equipment. But so many within the scope of use, often happen some failures: a, fault phenomenon: digital display table indicates a negative; Possible reasons: digital display table with pt100 thermocouple wiring is wrong or pt100 thermocouple have short circuit phenomenon; Processing method: correct wiring, or find out short circuit, reinforced insulation. Second, the failure phenomenon: pt100 thermocouple table indicating infinity; Possible reasons: pt100 thermocouple or lead wire short circuit or terminals to loosen, etc. ; Methods: the change in resistance or welding and tighten the screw connection, etc. Three, fault phenomenon: display pt100 thermocouple indicated value is lower than the actual value or values instability; Possible reasons: protecting tube with metal dust, dust, dirt and thermocouple short circuit between terminal; Methods: to remove scrap metal, cleaning dust, water, etc. , find the short circuit point reinforced insulation. Four, fault phenomenon: PT100 thermocouple value changes with the temperature relation; Possible reasons: pt100 thermocouple wire material corrosion metamorphism; Deal with method: change of pt100 thermocouple. High temperature accelerated electrons movement, increases the chances of electrons are scattered, so the object of heat resistance is higher. This explains why they tend to fuse at the moment of electricity. Cross sectional area of large, have more space for the metal electrons flow, so the resistance is smaller. Electronic across the metal generally more collision will happen, so long metal resistance is larger. Also has the properties of conductive electrolyte, but the conduction mechanism of electrolyte and metal is not the same. Why liquid depend on ion ( When an atom lose or get electronic will show the punctual or negative charges, this time we called after ionization ion) atoms The directional flow of and conductive. Liquid and air can be the main principle of ionization because of great gap between atoms or molecules. （ A glass of water and a glass of alcohol added together, the volume is not equal to them the algebraic sum of the original volume. This kind of situation can't happen on our solid and solid) In the electrolyte, the current is produced by the flow of charged ions, so the liquid resistance is affected by the concentration of salt. Such as distilled water are insulators, but salt water is a good electrical conductor. In the biological membrane in the body, is responsible for the transfer of a current ion salt. Will choose what of ion membrane of the small hole can get through it. This direct determination of membrane resistance. Temperature on the resistance of different materials have different absence made. Electrical conductor temperature close to room temperature, good conductor resistance value, usually is proportional to the temperature, the type of a known as the temperature coefficient of resistance. Semiconductor without doped semiconductor resistance varies with temperature drop, the two into a geometric relationships: a doped semiconductor change is more complicated. When the temperature rose from zero, the resistance of the semiconductor first reduce, to the vast majority of charged particles ( Electron or hole/hole) Left their carrier, resistance of electrically charged particles activity decreased with the temperature rise a little. When the temperature rise even higher, will generate new semiconductor carrier ( And without doped semiconductor) , the original carrier ( Due to permeability of mixed) Importance to drop, so the resistance will fall again. Insulator and electrolytes insulator and electrolytes generally out of proportion, the relationship between resistance and temperature and different materials have different changes, so not in the list of a general formula.