How to tell when a thermocouple input failure

Carried out in accordance with the instrument wiring diagram wiring right after electrify, first instrument display instrument of thermocouple indexing number, and then display instrument range, and then measuring instrument discharge of digital tube display set temperature, the digital tube display on the meter measuring temperature.

if digital tube display on the meter is not the temperature of the heating element, and show 'over', '0000' or '000' and so on, explain instrument malfunction, input parts should be done the following test:

a) The thermocouple from the meter thermocouple input to be removed, then the instrument with any wire thermocouple input terminal short circuit. On the electricity, instrument digital tube display value approximately at room temperature, thermocouple internal connection open circuit, the same type thermocouple should be changed. If still the status of the said above that instrument in the process of transportation, the input end of the instrument is damaged, to change the instrument.

b) The above fault instrument of thermocouple down, switch to run next to normal the same degree, access to the instrument of thermocouple, after electrify, the original fault instrument digital tube display on the heating element temperature, thermocouple internal connection open circuit, replace the same type thermocouple. If still the status of the said above that instrument in the process of transportation, the input end of the instrument is damaged, to replace the instrument.

c) The defective thermocouple removed from the instrument, measured with a multimeter in ohms ( r) * 1 file, use multimeter thermocouple at both ends, two table stick to test if the multimeter display on resistance value is very big, thermocouple internal connection open circuit, replace the same type thermocouple. Or have a certain value, the instrument input has a problem, should replace the instrument.

d) According to the instrument wiring diagram wiring is correct, if the instrument after electrify, digital tube display meter race such as negative phenomenon, access to meter the thermocouple '+' and '-' wrong. Just need to change.

e) Wiring correct instrument at run time, the temperature of the instrument on the digital tube display and the actual measurement of the temperature difference of 30 ~ 60 c c. Even bigger difference, the instrument of indexing, and thermocouple dividing, make a mistake. By thermocouple index number b, s, k, e, such as thermocouple temperature ( º c) With the millivolt ( mv) The value of the corresponding relation, the same temperature ( º c) The case, the millivolt values ( mv) B the minimum degree, s degree, small, k index number is larger, e index number, the largest discriminant according to this principle. Knowledge

:

the thermocouple four basic law

the working principle of thermocouple thermal resistor

the causes of measurement errors of thermocouple compensation wire type and function of the

processing method of the cold junction of the thermocouple thermocouple temperature measurement principle