In what situation does a two-wire thermal switch remain operable?

A two-wire thermal switch is designed to operate based on the flow of current through its sensing loop. In this scenario, it is critical to understand how the switch functions in relation to the configuration of the loops.

When one loop is either open or shorted, the thermal switch can still remain operable. This condition implies that the circuit can still be completed or disrupted, allowing the switch to respond appropriately to changes in temperature. The thermal switch relies on the difference in resistance or current flow resulting from the thermal changes, and if one loop is still intact, it can continue to function as intended.

In contrast, if both loops are shorted, the current would bypass the thermal switch, potentially rendering it non-functional. Similarly, when both loops are working perfectly, while it may seem advantageous, this does not specifically highlight the operational scenario of the thermal switch's response in varied conditions. When not connected to power, the thermal switch simply cannot operate at all, as it relies on power supply for its operation.

Thus, the situation where one loop is open or shorted allows at least a partial operability due to the presence of an intact pathway, which is why this scenario aligns with the functionality of the two-wire thermal switch.