Fault identification and decomposition of thermocouples

Method for identifying faults in thermocouple input:

1.1) After correctly wiring and powering on according to the instrument wiring diagram, the instrument first displays the thermocouple index number of the instrument, followed by the instrument range. The digital tube under the instrument displays the set temperature, and the digital tube on the instrument displays the measured temperature. If the counter on the instrument does not indicate the temperature of the heating element& ldquo; OVER” & ldquo; 0000” Or“ 000” Please indicate that there is a malfunction in the instrument input section and perform the following checks

Remove the thermocouple from the input side of the instrument thermocouple and short-circuit the input side of the instrument thermocouple with any wire. When powered on, if the display value of the counter tube on the instrument is around room temperature, it indicates that the internal wiring of the thermocouple has been opened and replaced with a thermocouple of the same type. If the above situation occurs, it indicates that the input side of the instrument is damaged during transportation and needs to be replaced.

1.3) Remove the thermocouple of the above-mentioned fault meter and exchange it with a thermocouple connected to the same type of dial gauge that operates normally horizontally. After powering on, if the dial gauge of the original fault meter displays the temperature of the heating element, it indicates that the internal wiring of the thermocouple is open and exchanged with a thermocouple of the same type. If the above situation occurs, it indicates that the input side of the instrument is damaged during transportation and needs to be replaced.

1.4) Remove the faulty thermocouple from the instrument, measure the ohm (R) * 1 segment with a tester, and measure the two ends of the thermocouple with the two rods of the tester. If the resistance value of the tester is high, it indicates that the internal connection of the thermocouple is disconnected, and replace it with a thermocouple of the same type. Otherwise, please indicate that there is a resistance value and there is a problem with the input side of the instrument. Replace the instrument.

2) Connect the wires correctly according to the instrument wiring diagram. After the instrument is powered on, the instrument displays negative values, etc. Connect the thermocouple to the instrument+& rdquo; and“ -& rdquo; Because you were wrong. Just replace it.

When wiring and operating the correct instrument, the temperature of the digital tube on the instrument differs from the actual measured temperature by 30 º C to 60 º C. This further indicates that the difference is significant, and the index number of the instrument is different from that of the thermocouple. The temperature of the thermocouple, such as the division codes b, s, k, º; c) From the correspondence with the milliampere (MV) value, under the same temperature (º; c), it can be determined that the millimeter wave generated has the lowest B index number, lowest s index number, highest k index number, and highest e index number (MV).