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Heating furnace combustion controls a few kinds of main commonly used measuring
From;    Author:Stand originally

(1) thermocouple: The principle of thermocouple is, when two kinds different conductor or semiconductor join are become close when loop, if two contact temperature is different, hot electromotive force can appear in loop, produce electricity.

The pyroelectricity power volume of thermocouple not only with measure upright temperature to concern, still carry on freedom definitely (Leng Duan) temperature.

Introduce the add electromotive force that along with Leng Duan temperature changes one in circuit normally in measuring meter, compensate the change of Leng Duan temperature automatically, measure precision in order to assure. Considering change send implement leave measurement point further normally, when using more expensive thermocouple, if use heat idol silk to be brought to from measurement point completely change send implement, the price is too high. For managing, choose on industry fall in inferior temperature (100 ℃ are the following) of as characteristic as the pyroelectricity that uses thermocouple close cheap metal, regard heat idol silk as the substitute in microtherm area, call compensation lead, so heat idol silk should be brought to temperature only the place under 100 ℃ went, the length of the others can come with cheap compensation lead outspread.

Thermocouple model basically has K according to measuring lukewarm limits to differ model, S, B etc.

(2) temperature changes send implement: Temperature changes send implement the main effect of input is thermocouple compensation of Leng Duan temperature and adjusted at 0 o'clock. Outputting circuit basically is the millivolt signal thermocouple changeover is standard signal (the voltaic signal that uses 4 ~ 20mA commonly) , convey to control unit to the temperature from the back. 

(3) discharge orifice plate: Action is to detect two side are losing orifice plate take the difference that presses a mouth to press signal.

(4) shedding quantitative change sends implement: The difference that detects orifice plate presses signal to change the voltaic signal that is 4 ~ 20mA, send flow control unit.

(5) pressure changes send implement: the pressure signal that takes the place that press a mouth to detect changeover is the voltaic signal of 4 ~ 20mA. 

(6) thermal resistance: Thermal resistance is the character that changes along with temperature according to the resistor of metallic conductor undertake measuring lukewarm. When measuring the temperature under 150 ℃ , because the electromotive force of thermocouple is lesser, often use thermal resistance to measure temperature. Heating furnace supports combustion the temperature of fan drive detects and heating furnace pace detects into the temperature of bridge those who use is thermal resistance (PT100) . Thermocouple of thermal resistance unlike needs Leng Duan temperature to compensate in that way, measure precision taller also, apply to - 500 ℃ of ~ of 200 ℃  the temperature inside limits detects. 
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