Low-Power Instrument Transformers (LPITs), split into Low-Power Voltage Transformers (LPVTs) and Low-Power Current Transformers (LPCTs), are increasingly shaping the future of smart grid infrastructure. While their technical advantages, compact size, reduced material use, and sustainability, have been well established, the decisive factor for utilities lies in their broad range of real-world applications. By enabling more flexible, accurate, and safe measurement and protection functionalities, LPITs are proving to be essential components across the entire energy value chain.
This article highlights four major application areas where LPITs provide clear benefits: monitoring, high-accuracy measurement, protection, and power quality.
Monitoring Applications
Traditional monitoring of grid assets such as transformers and switchgear has often been constrained by the size and handling complexity of conventional instrument transformers. LPITs overcome these barriers by offering compact designs and safer output levels, which greatly simplify installation and operation.
In transformer and switchgear analysis, LPITs deliver sufficient accuracy for identifying loading patterns, operational stresses, and potential degradation trends. By feeding this data into predictive maintenance algorithms, utilities can shift from reactive to condition-based asset management strategies.
A critical advantage in monitoring applications is personnel safety. Conventional ITs often expose technicians to hazardous voltages during installation or maintenance. LPITs, on the other hand, operate with significantly reduced output levels, making them inherently safer. This increased safety encourages more widespread deployment of monitoring devices, ultimately improving visibility across the grid.
High-Accuracy Measurement
LPITs are not limited to secondary monitoring but also play a central role in high-precision applications. Their improved linearity and extended bandwidth enable billing-grade measurements, which are crucial for utilities and end customers alike.
In customer billing, LPITs ensure fair and transparent energy accounting, especially in environments where distributed energy resources (DERs) such as solar photovoltaics or wind turbines feed into the grid. Their accuracy helps utilities properly measure bi-directional power flows, an essential requirement in modern grids.
Moreover, LPITs support advanced grid planning and optimization. Their scalable deployment provides utilities with a granular understanding of load flows, enabling better forecasting and long-term infrastructure planning. For renewable integration, LPITs ensure that variable generation sources are measured precisely, supporting algorithms for balancing and dispatching energy in real time.
Protection Applications
Protection of both equipment and the grid remain one of the most mission-critical applications of instrument transformers. LPITs deliver significant advantages in this domain due to their fast adaptability, and reliability.
Earth-fault monitoring is a prime example. LPITs enable accurate detection of ground faults, even under low-current conditions, ensuring that protective relays can trip effectively and minimize damage. Similarly, LPITs enhance overvoltage protection by reliably capturing transient events that could otherwise remain undetected.
Another critical use case is equipment protection. By monitoring current and voltage at critical nodes, LPITs provide real-time data to relays and automation systems, helping prevent cascading failures. Their compatibility with IEC 61850-based communication protocols further strengthens their role in adaptive protection schemes that require fast, interoperable data exchange across substations.
Power Quality Applications
With the growing prevalence of inverters, electric vehicles, and non-linear loads, maintaining grid power quality has become increasingly challenging. LPITs, with their wide frequency response and ability to capture harmonics, offer a valuable solution.
In harmonics measurement, LPITs provide detailed insights into distortion levels, enabling utilities to mitigate negative effects on sensitive equipment and reduce energy losses. Their role in measuring frequency correctly for frequency stability algorithms is equally critical, as maintaining system frequency is vital for grid stability, particularly in renewable-rich networks.
Voltage sag detection is another area where LPITs excel. By enabling precise algorithms to identify and characterize sags, LPITs help utilities prevent malfunctions in industrial processes and improve resilience in critical infrastructure.
Conclusion
The versatility of LPITs makes them indispensable in modern smart grids. From enhancing safety in monitoring applications to enabling billing-grade precision, protecting assets, and ensuring power quality, LPITs go far beyond being a sustainable alternative to conventional instrument transformers. They are, in fact, catalysts for digitalization and optimization of the grid.
As utilities worldwide scale up their deployment, LPITs will continue to drive improvements in reliability, efficiency, and adaptability, cementing their role as a cornerstone of future-proof energy systems.
Key Takeaways on LPIT Use Cases
Monitoring: Safer, compact LPITs enable asset analysis, predictive maintenance, and improved grid visibility.
High-Accuracy Measurement: Billing-grade precision supports DER integration, customer fairness, and grid optimization.
Protection: Fast, reliable fault detection and equipment protection enhance resilience and reduce damage risk.
Power Quality: LPITs capture harmonics, frequency deviations, and voltage sags for improved stability and reliability.
Scalability: Flexible deployment ensures utilities can adapt LPITs across monitoring, protection, and optimization tasks.
Installation Examples:
The following figures highlight real-world LPIT installations in substation environments. Figure 1 illustrates a typical retrofit installation inside the blind plug side of a deadbreak. Thanks to the compact design, LPVT could be integrated without requiring any modification to the existing switchgear cabinet. Figure 2 demonstrates the installation of an LPVT directly on top of existing busbars. The device’s lightweight construction and small dimensions enable reliable voltage measurements even in highly constrained spaces. Figure 3 presents a combined LPVT and LPCT mounted on a loadbreak switch, showcasing the versatility of LPITs for diverse installation scenarios:
Figure 1: Retrofit installation of an LPVT in the blind plug side of a deadbreak, requiring no cabinet modifications.
Figure 2: LPVT mounted on existing busbars, enabling voltage measurement in confined spaces.
Figure 3: Combined LPVT and LPCT on a loadbreak switch, demonstrating product versatility.
