underwound

Underwound refers to a winding that has fewer turns, or less energy storage, than designed. The term is used in both electrical engineering and mechanical contexts to describe a coil, transformer, motor winding, or spring that has not been wound to its intended extent. The opposite condition is typically described as overwound or over-wound.

In electrical devices, underwinding affects magnetic and electrical performance. Fewer turns reduce inductance and the magnetic flux generated for a given current, which can weaken voltage output, torque, or other rated performances. If a circuit uses a fixed voltage source, an underwound coil can draw more current than intended, potentially causing overheating, higher losses, and poorer regulation. Conversely, underwinding can also raise the risk of core saturation in transformers or inductors when operated at or near design voltage and frequency. The specific impact depends on the device, operating conditions, and the degree of underwinding.

In mechanical applications, such as mainsprings in watches or clocks, underwinding means the spring is not wound tightly enough, providing less stored energy. This typically results in a shorter running time or weaker torque and may cause uneven performance.

Causes of underwinding include manufacturing tolerances, damage, wear, maintenance errors, or deliberate design choices for special applications. Detection methods include counting turns, measuring resistance, or testing inductance and performance under load. Remedies range from re-winding or replacing the component to adjusting operating conditions to accommodate the winding level. See also overwound for contrast.