Thermal resistance (Thermal Resistor) it is medium the detector of a kind of temperature with microtherm the most commonly used area. Thermal resistance is measured lukewarm be to be based on a metal to the resistance of conductor follows the addition of temperature and increase this one character to undertake temperature is measured. Its main characteristic is to measure precision tall, performance is steady. Among them the measurement of platinum thermistor accuracy is highest, it applies extensively at industry to measure not only lukewarm, and be made fiducial appearance of the standard. Thermal resistance is made by pure metal stuff mostly, application is at present most is platinum and copper, in addition, already began to use the material such as nickel, manganese and rhodium to create thermal resistance now. The sort of feeling lukewarm material with metallic commonly used thermal resistance is more, the most commonly used is platinic silk. Industry is measured outside dividing platinic silk with material of metallic thermal resistance, still nickel of copper, nickel, — of iron, iron waits.

 

 

Resistance changes along with temperature and change this one character will measure temperature and the parameter that concern with temperature. Thermal resistance is made by pure metal stuff mostly, application is at present most is platinum and copper, already began to use the material such as nickel, manganese and rhodium to create thermal resistance now. Thermal resistance needs to transmit resistor signal to computer control equipment through down-lead normally or other on 2 appearance.

 

From thermal resistance measure lukewarm principle knowable, the change that is worth through thermal resistance block directly will measure the change of the temperature that be measured, accordingly, the change of all sorts of lead resistor such as the derivative line of thermal resistance body can be measured to temperature bring an influence.

 

 

Armored thermal resistance is by feeling lukewarm component (resistor body) , the substantial put oneself in another’s position that bushing of down-lead, insulating material, stainless steel is combined and becomes, its external diameter is φ2 commonly- – φ8mm, the smallest can amount to φmm. With common model thermal resistance photograph is compared, it has following advantage:

 

1, volume is minor, interior does not have empty air gap, heat is inertial go up, measure lag small;

2, mechanical performance is good, be able to bear or endure brace up, fight concussion;

3, can bend, facilitating installation;

4, service life is long.

 

 

End panel thermal resistance feels lukewarm component is circled by the resistor silk material of special processing make, clingy in thermometric end panel. It and general axial thermal resistance are compared, can reflect the actual temperature of the end panel that be measured more correctly with apace, apply to the end panel temperature that measures plain bearing liner and other parts.

 

 

Lie between explode model the wiring box that thermal resistance adopts special structure, its crust interior because volatile gas mixture is in inside wiring box by the scintilla or electric arc explosion confine that affect and happens, manufacturing site won’t be brought exceed explosion. Lie between explode model thermal resistance can be used at Bla- – the temperature that hazardous area has inside B3c class area is measured.

 

 

Of thermal resistance those who measure lukewarm principle and thermocouple those who measure lukewarm principle to differ is,

 

The fuel factor that is based on resistor undertakes temperature measures thermal resistance, what the block value of resistor body follows the change of temperature and change namely is characteristic. Accordingly, want to measure the block that gives feeling lukewarm thermal resistance to be worth change only, can measure a temperature. Basically have metallic thermal resistance and semiconductor thermal resistor at present two kinds.

 

The resistance of metallic thermal resistance and temperature can use the following approximate relation to express commonly, namely

 

Rt=Rt0 [1+α (T-t0) ]

 

In type, rt is the block value when temperature T; Rt0 is temperature T0 (normally T0=0 ℃ ) when corresponding resistance; α is temperature coefficient.

 

The block value of semiconductor thermal resistor and temperature relation are

 

Rt=AeB/t

 

The Rt in type is the block value when T for temperature; A, B depends on the constant of the structure of semiconductor material.

 

Be compared and character, the temperature coefficient of thermal resistor is bigger, the resistor watch below normal temperature is tall (be in thousands of Europe normally above) , but interchangeability is poorer, nonlinear serious, measure lukewarm limits to have only – 50~300 ℃ left and right sides, a large number of at home appliance and car detect with temperature and be being controlled using. Metallic thermal resistance is applied to commonly – the temperature inside 200~500 ℃ limits is measured, its characteristic is to measure accurate, stability good, function is reliable, the application in Cheng control is extremely wide.

 

In light of the change that thermal resistance of commonly used metal follows temperature from resistor on industry, major metal conductor has this individual character to pledge, but not be can use as measure tepid resistance, regard the metallic stuff of thermal resistance as general requirement: As far as possible rate of big and stable temperature coefficient, resistor wants greatly (the size that reduces sensor below same sensitivity) , good, resistance follows the duplicate sex of the chemical physics property that has stability inside used temperature range, material temperature.

 

 

Temperature sensor thermal resistance is medium the detector of a kind of temperature with microtherm the most commonly used area. Its main characteristic is to measure precision tall, performance is steady. Among them it is highest that platinum heats up be block to measure accuracy, it applies extensively at industry to measure not only lukewarm, and be made fiducial appearance of the standard.

 

 

Temperature sensor thermal resistance is measured lukewarm the resistance that is based on metallic conductor follows the addition of temperature and increase this one character to undertake temperature is measured. Temperature sensor thermal resistance is made by pure metal stuff mostly, application is at present most is platinum and copper, in addition, already began to use the material such as pasture, nickel, manganese and rhodium to create temperature sensor thermal resistance now.

 

 

(1) perfectness model industry of temperature sensor thermal resistance is commonly used temperature sensor thermal resistance feels lukewarm component (resistor body) structure and characteristic see watch 2-1-11. From temperature sensor thermal resistance measure lukewarm principle knowable, the change of the temperature that be measured is to pass the change that block is worth temperature sensor thermal resistance to measure directly, accordingly, the change of all sorts of lead resistor such as the derivative line of body meets temperature sensor thermal resistance be measured to temperature bring an influence. Be the same as to remove the effect of down-lead resistor kind use 3 lines to make or 4 lines are made, refer to about specific content a the 3rd chapter the first.

 

(2) armored temperature sensor thermal resistance is armored temperature sensor thermal resistance is by feeling lukewarm component (resistor body) , the substantial put oneself in another’s position that bushing of down-lead, insulating material, stainless steel is combined and becomes, if graph 2-1-7 place is shown, its external diameter is φ2~φ8mm commonly, the smallest can amount to φmm.

 

With common model temperature sensor thermal resistance is compared, it has following advantage: ① volume is minor, interior does not have empty air gap, heat is inertial go up, measure lag small; ② mechanical performance is good, be able to bear or endure brace up, fight concussion; ③ can bend, service life grows facilitating installation ④ .

 

(3) thermal resistance of sensor of temperature of end panel of thermal resistance of sensor of end panel temperature feels lukewarm component is circled by the resistor silk material of special processing make, clingy in thermometric end panel, its structure is shown like graph 2-1-8 place. It and thermal resistance of sensor of general axial temperature are compared, can reflect the actual temperature of the end panel that be measured more correctly with apace, apply to the end panel temperature that measures plain bearing liner and other parts.

 

(4) lie between explode model temperature sensor thermal resistance is lain between explode model the wiring box that temperature sensor thermal resistance adopts special structure, its crust interior because volatile gas mixture is in inside wiring box by the scintilla or electric arc explosion confine that affect and happens, manufacturing site won’t be brought exceed explosion. Lie between explode model the temperature that temperature sensor thermal resistance can use within Bla~B3c class area to have hazardous area is measured.

 

Temperature sensor thermal resistance measures lukewarm system to wait for composition with indication appearance by lead of temperature sensor thermal resistance, join commonly. Must notice the following at 2 o’clock:

 

Thermal resistance of ① temperature sensor and the graduation number of indication appearance must agree

 

The influence that ② changes to eliminate join lead resistor, must use 3 lines to make receive a standard. Specific content is referred to a the 3rd chapter.

 

(2) armored temperature sensor thermal resistance is armored temperature sensor thermal resistance is by feeling lukewarm component (resistor body) , the substantial put oneself in another’s position that bushing of down-lead, insulating material, stainless steel is combined and becomes, if graph 2-1-7 place is shown, its external diameter is φ2~φ8mm commonly, the smallest can amount to φmm. With common model temperature sensor thermal resistance is compared, it has following advantage: ① volume is minor, interior does not have empty air gap, heat is inertial go up, measure lag small; ② mechanical performance is good, be able to bear or endure brace up, fight concussion, ③ can bend, service life grows facilitating installation ④ .

 

(3) thermal resistance of sensor of temperature of end panel of thermal resistance of sensor of end panel temperature feels lukewarm component is circled by the resistor silk material of special processing make, clingy in thermometric end panel, its structure is shown like graph 2-1-8 place. It and thermal resistance of sensor of general axial temperature are compared, can reflect the actual temperature of the end panel that be measured more correctly with apace, apply to the end panel temperature that measures plain bearing liner and other parts.

 

(4) lie between explode model temperature sensor thermal resistance is lain between explode model the wiring box that temperature sensor thermal resistance adopts special structure, its crust interior because volatile gas mixture is repaired the length that should change resistor silk necessarily by the open circuit of the shadow resistor body such as scintilla or electric arc and influence resistance, change for this new resistor system had better, if use,solder repair, the ability after solder hind wants desired result qualification is used

 

As the development of the times, scientific research, agriculture, warm connect, the industrial department such as spin, computer room, aerospace, electric power, need to use humidity sensor more and more, jump over to producing the requirement that tastes quality to exceed trade tall, the control of lukewarm to the environment, humidity and monitor to what portion of industrial data water is worth already made one of more general technology requirements with the analysis. Humidity sensor product and humidity are measured attribute the trade with 90 arisen time. How to use good humidity sensor, how to judge the performance of humidity sensor, this is told to average user, still be a relatively complex technology issue.

 

 

Humidity sensor, cent is resistor type and capacitance type two kinds, the basic form of the product is in base piece wet material of besmear Fu feeling forms feeling wet film. The water vapour in air is adsorptive after feeling wet material, constant of the impedance of component, medium produces very big change, make Shi Min component thereby.

 

Domestic and international the level of humidity sensor product of each manufacturer is differ, quality value differs bigger, how does the user choose the good product with optimum performance/price ratio to have certain difficulty truly, need makes thorough knowledge in this respect. Humidity sensor has following characteristics:

 

 

The precision of humidity sensor should achieve ±2%~±5%RH, this level regards short of as very hard metrological implement use, the precision that humidity sensor wants to achieve ±2%~±3%RH is more difficult, the character that gives out in product data normally is in normal temperature (℃ of 20 ℃ ±10) He Jie measures in only gas. In be used actually, as a result of dust, smeary the influence that reachs harmful gas, use time grows, can produce ageing, precision drops, the precision level of humidity sensor should combine his long-term stability goes judging, say commonly, long-term stability and service life are the first class issue that affects humidity sensor quality, year drift capacity control is in the product of 1%RH level is very few, control in ±2% commonly, taller even.

 

 

Shi Min component is divided sensitive to environmental humidity outside, to temperature also very sensitive, its temperature coefficient is commonly inside 0.2~0.8%RH/ ℃ limits, and some Shi Min component fall in different relative humidity, its temperature coefficient has a difference again. Wen Piao is nonlinear, this need adds temperature to amend form on circuit. Use sheet piece machine software compensation, or having sensor of temperature compensatory humidity is guarantee against of the precision of completely lukewarm limits, the linearization of curve of humidity sensor Wen Piao affects compensatory result directly, nonlinear Wen Piao often does not amend the result with go out better, use hardware temperature to follow only sexual compensation just can achieve actual compensation result. The temperature limits that humidity sensor works also is important parameter. Element of most Shi Min works normally in 40 ℃ above hard.

 

 

Metallic oxide pottery and porcelain, the Shi Min material such as high polymer polymer and chloridize lithium brings to bear on when volts d.c. , can cause performance change, even invalidation, so sensor of this kind of humidity cannot use volts d.c. or the alternating voltage that have dc component. Must be alternating current power supply.

 

 

Current, humidity sensor is existing generally the phenomenon with poor interchangeability, the sensor of same type cannot crossing-over, affected use result badly, to maintenance, debug increased difficulty, some manufacturer made a variety of effort in this respect, (but interchangeability still very poor) obtained better result.

 

 

It is difficult that corrective humidity should compare corrective temperature much. Temperature demarcate often makes a standard with thermometer of a standard can, and the demarcate standard of humidity comes true harder, thermometer of dry wet ball and pattern of a few familiar pressing with a finger are hygroscopic be to cannot use demarcate, precision cannot assure, because its ask ambient conditions is very severe, general situation, (below the requirement that had better fit in humidity environment) when the calibrating equipment that perfects in lack, use method of simple calibrating of saturated salt solution normally, measure its temperature.

 

 

In humidity sensor the circumstance of actual demarcate difficulty falls, can have judgement of humidity sensor function and examination through a few simple methods.

 

1, consistency decides, same kind, the humidity sensor product of same manufacturer had better buy two above, show an issue more more more, put electrify together to detect quite output value, below relatively stable condition, observe the consistency of the test. If detect further, can record for some time in the interval inside 24h, have commonly inside a day tall, medium, low 3 kinds of humidity and temperature circumstance, can the consistency of product of observation of more comprehensive ground and stability, include temperature to compensate character.

 

2, use mouth breathe out or use other to add wet method to sensor wet, observe its sensitivity, repeatability, rise performance of wet releasing of moisture, and resolution, the highest span of the product.

 

3, make to the product box and pass a test of two kinds of circumstances. Whether to agree quite, observe condition of its fuel factor.

 

4, mix in high temperature condition to the product microtherm condition (according to manual standard) have a test, restore to fall to whack detect and the record before the experiment is made quite, the temperature adaptability of check product, observe the consistency condition of the product.

 

The function of the product wants a basis finally to pledge check branch detects completely normally method. Use saturated salt solution to make demarcate, also can use famous brand product to make detect than be opposite, the product still should undertake more comprehensive ground judges the quality of humidity sensor use the long-term demarcate talent in the process for a long time.

 

 

Products of many sensor of domestic and international humidity appeared on home market, component of capacitance type Shi Min is relatively much see, sort of feeling wet material basically is high polymer polymer, chloridize lithium and metallic oxide. The advantage of component of capacitance type Shi Min depends on answering speed fast, bulk small, degree of linearity is good, stabler, foreign some products still have high temperature character of service. But the product that achieves afore-mentioned performance is foreign famous brand more, the price is higher. The product of low of component of Shi Min of type of a few capacitance that sells on the market, often short of afore-mentioned levels, degree of linearity, consistency and repeatability are very not ideal, 30%RH is the following, 80%RH above feeling is humid paragraph be out of shape serious. Some products use sheet piece machine compensation is amended, make humidity appears “ rank the leap that leaps ” sex, make loss of accuracy, the defect that poor, linear differs occurrence consistency. No matter the component of capacitance type Shi Min of high quality scales or low class, long-term stability is not ideal, most and long-term use drift is serious, look of Shi Min capacitance is worth change to be PF class, the change of 1%RH is not worth 0.5pF, the drift that holds a cost changes the error that often causes a few RH% , component of Shi Min of most capacitance type does not have the property of the job below temperature of 40 ℃ above, often invalidation and attaint.

 

Shi Min component defies capacitance pattern corrode ability more defective also, often be opposite of the environment clean degree of demand is higher, some products return the phenomenon such as existence illumination invalidation, electrostatic invalidation, metallic oxide is resistor of Shi Min of pottery and porcelain, have the advantage with Shi Min identical capacitance, below environment of Dan Chen dust, stoma of pottery and porcelain is sealed to block component up to be met invalidation, the method that often uses electrify to remove dust will handle, but the effect is not quite ideal, and in combustible explode easily cannot use below the environment, alumina feeling wet material cannot overcome the weakness of ” of natural ageing of “ of its surface structure, impedance is not stable, shi Min resistor puts pottery and porcelain of metallic oxygen content in the weakness with long-term poor stability as much.

 

Resistor of chloridize lithium Shi Min, having the most outstanding advantage is long-term stability extremely strong, because this passes strict craft to make, the instrument that makes and sensor product can achieve taller precision, stability is strong it is the product has good degree of linearity, precision and consistency, assure be long-term service life reliably. The wet material of feeling of long-term stability other of Shi Min component still cannot replace chloridize lithium.