Title: Application of the principle of galvanic
FromElec-intro
Time:Wed, 11 Feb 2009 05:54:53 +0000
Author:Tiny
URL:http://www.elec-intro.com/Application-principle-galvanic/

Content:
galvanic application of the principle of thermocouple is the industry's most commonly used one of the temperature detection devices. The advantage is:  high-precision measurements. Thermocouple as a result of direct contact with the measured object, from among the media.  wide range. Commonly used thermocouple from -50 ~ 1600   can be continued while surveying, some of the special thermocouple to the lowest measurable -269   (such as nickel-chromium Jin), up to 2800   (such as tungsten - Re).  simple and easy to use. Thermocouples are often made from two different kinds of wire, but not at the beginning of the size and limitations, outside the protection of casing, it is very easy to use.1. The basic principles of thermocouple temperaturetwo different conductor or semiconductor materials A and B welded together to form a closed loop , 2-1-1 figure byshow. When the conductor of the A and B two points persistent 1 and 2 between the temperature difference, between the two will have a force, which into form a loop in the size of the current, a phenomenon known as the thermal effect. Thermocouple is the use of this effect to workmade.2. Thermocouple type of structure and the formation of(1) the type of thermocouplecommon thermocouples and thermocouple standards can be divided into two major categories of non-standard thermocouple. The call is the national standard thermocouplestandards for its thermal power and temperature , To allow error, and there is a uniform standard form of sub-degree thermocouple, whichhave showed their support of the instruments available for selection. Thermocouple in the use of non-standardized order of magnitude or scope of the standard and notof thermocouple, in general there is no uniform grading scale for the measurement of certain special occasions.standardization of China's thermocouple from January 1, 1988, the thermocouple and heat resistance by all international standards IEC production, and designated S, B, E, K, R, J, T standardization of seven thermocouple China-based design for the reunification of the thermocouple.(2) thermocouple in the form of the structure of the thermocouple in order to ensure a reliable, steady work, it follows the structure of the request:  thermocouple two fever component of welding electrodes must be strong;  hot electrode between the two should be well insulated to prevent a short circuit;  compensation thermocouple wire with the free end of the connection to reliable and user-friendly;  should be able to guarantee the protection of casing hot electrode and harmful media full isolation.3. Thermocouple cold junction temperature compensationas a result of the thermocouple materials in general are more expensive (especially when the use of precious metals), and the temperature to a point very far away from the instrument, the thermocouple in order to save materials, reduce costs, compensation is usually used to wire thermocouple The cold side (free end) into the relatively stable temperature control room, connected to the terminal on the instrument. It must be pointed out, the thermocouple wire compensation only an extension of the role of the hot electrode, so that the thermocouple cold end to the control room of the mobile terminal on the instrument itself can not eliminate the cold-side temperature of temperature, can not afford to compensate Role. Therefore, the need to adopt amendments to other methods to compensate for the cold-side temperature t0   0   when the temperature measurement.in compensation for the use of thermocouple wire should be noted that when the match type, can not pick the wrong polarity, the Compensation and thermocouple wire to connect the terminal temperature should not exceed 100  . 



 


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