Underground: Unseen but Safe
A large public utility company operated a significant number of underground transformers, installed in vaults beneath manhole covers, located in residential neighborhoods. The problem was: many of these transformers were more than 40 years old, and over time, their age had begun to present serious safety concerns.
In several instances, debris buildup caused transformers to overheat, leading to dangerous pressure increases and, in some cases, manhole covers being blown off entirely. With these issues becoming a serious risk to the public, the utility needed a reliable way to monitor transformer health to detect temperature fluctuations and potential failures before they became hazardous.
Building on our proven above-ground temperature monitoring technology, we developed a compact, underground-ready solution. The system pairs a high-resolution temperature sensor with a small transmitter via a short cable. For subterranean use, the unit was modified with a sealed enclosure in place of the solar panel and equipped with a long-life battery pack designed for extended operation in enclosed environments.
With an efficient software and data management system, each monitoring unit can operate continuously for more than 10 years on a single small battery. Temperature data is transmitted periodically to our secure server and forwarded to the utility’s monitoring system. Automated alarms notify operators when temperatures rise above normal thresholds, prompting immediate dispatch if a critical limit is reached.
With recent enhancements to the system, an innovative power-harvesting feature, a small current transformer (CT) is clamped around the power cables inside the vault. This allows for continuous energy generation and uninterrupted operation with no need for battery replacement. Our efficient circuitry and low-power software design enable near real-time data transmission, even when powered by the minimal energy available from the CT, roughly the equivalent of what could power a small household toaster.
