NRCC Instrumentation Practice Test

Thermocouple types are named by the metal pairs that make up the junction, and each type has its own characteristic sensitivity and operating range. The set with J, K, and T is the best choice because these three are the most commonly used in general instrumentation, offering a good mix of sensitivity, cost, and a wide usable temperature span. J is iron–constantan, good for moderate temperatures; K is chromel–constantan, versatile for a wide range; T is copper–constantan, excellent at low temperatures with high stability. Together they cover a broad range and are standard references in many manuals and specifications. Other options list other valid thermocouple types as well, including high-temperature noble-metal types, but J, K, and T are the trio most frequently emphasized for typical instrumentation work due to their balance of performance and practicality.