Question

In a thermo couple, the temperature of the cold junction and the neutral temperature are $-{40}^{\circ }C$and ${275}^{\circ }C$ respectively. If the cold junction temperature is increased by ${60}^{\circ }C$, the neutral .temperature and temperature of inversion respectively become

• A. ${275}^{\circ }C,{530}^{\circ }C$
• B. ${355}^{\circ }C,{530}^{\circ }C$
• C. ${375}^{\circ }C,{590}^{\circ }C$
• D. ${355}^{\circ }C,{590}^{\circ }C$

Answer 1

Answer: (A)

${275}^{\circ }C,{530}^{\circ }C$

When the temperature of cold junction is increased,the neutral temperature remains constant for a given thermocouple and it is independent of the temperature of the cold junction.

Therefore ${\theta }_n={275}^{\circ }C$

We know that ${\theta }_i=2{\theta }_n-{\theta }_c$

$=2\times 275-(-40+60)$

$=550-20={530}^{\circ }C$