When the U.S. electric grid was built in the 1890s, no one could’ve foreseen the extent to which we all now rely on the power that flows across transmission lines, through substations and transformers, and other systems so we can light up office buildings, stream movies, and much more. That’s why smart grid technologies—which bring automation, two-way communication between utilities and customers, and sensing along transmission lines—are essential for today’s energy demands.
Since high uptime and reliability are more critical than ever, how do you quickly and accurately detect and repair faults on the grid?
This was the burning question in China, which, not surprisingly, leads the world in electricity infrastructure development and smart grid technologies. A power company there needed a more effective current fault sensor solution. Building their own solution would’ve required integration of multiple components, including microcontrollers, amplifiers, analog-to-digital converters (ADCs), and more—a complex and costly proposition.
Their key criteria? The solution needed to consume very little power because the sensors, located on a power line, would generally receive energy from either batteries or nearby fiber optic lines (Typically, current sensors don’t readily have the required power to operate in a substation where 110VAC/220VAC would be prevalent). High performance and accuracy were also important, given that the sensors are evaluating the health of the grid during faults as well as normal operation.
The power company found its answer in Maxim’s electronic current transformer/electronic potential transformer (ECT/EPT). This current fault sensor, also known as MAXREFDES38#, can be placed on multiple points on the grid, providing granular results that can help power companies act faster to keep the electricity flowing (Figure 1 shows the system board for this reference design.)
MAXREFDES38# system board
Integrating components including a three-channel analog switch, a quad precision low-power buffer, and a 16-bit fully differential ADC, the solution typically operates at less than 85mW and is roughly the size of a credit card. This analog front-end is also very accurate, making it ideal for fault sensor applications that call for low-power, highly accurate data conversion.
In fact, such a current fault sensor can be integrated into an older utility infrastructure to make that infrastructure smarter. By adding smart sensors to the mix, utilities can reduce the cost of any outages.