Pulse Electronics DI/DT current sensors used with ST's ICs to boost metering accuracy

SAN DIEGO, USA: Pulse Electronics Corp., a leading provider of electronic components, has collaborated with STMicroelectronics, one of the world’s largest semiconductor manufacturers and a leader in chips for smart metering, on research testing the accuracy of current sensing in metering applications. The application note, "Current sensing in metering applications using a Pulse Electronics current sensor and ST metering devices," is now available on the Pulse Electronics and STMicroelectronics websites.

The study tested STMicroelectronics' STPMxx metering devices using several different current sensors. Pulse Electronics' di/dt current sensor, based on the Rogowski coil principle, offered exceptional linearity over a wide current range. When used with STPMxx ICs, the accuracy of the meter is boosted, meeting the Class 0.2 S accuracy limits defined by the IEC 62053-22 meter standard for currents from 0.1 A to 200 A.

“STPMxx presents multiple benefits because of a proprietary power calculation and digital signal processing algorithm developed specifically for Rogowski coil-based sensors and the capability of mutual current compensation when multiple sensors are used,” explained Giuseppe Privitera, energy metering application manager, Industrial and Power Conversion Division, STMicroelectronics.

"While the Rogowski coil principle is well-known and has been widely implemented in various current sensing devices, the engineering challenge has been to control the winding characteristics to achieve the accurate current measurements required for metering applications," said Gerard Healy, field application engineer at Pulse Electronics Europe and co-author of the paper with Privitera.

"Pulse Electronics has developed a precision winding technique that controls the parameters which directly influence the output voltage. A patent-pending segmented winding approach allows for a high number of winding turns per unit length to provide a sufficiently large output voltage for detection and integration. Pulse's winding configuration meets Class 1 requirements for immunity to external magnetic fields and an additional Faraday shield over the winding prevents electrostatic voltage coupling from the AC voltage of the conductor.”

The Pulse Electronics current sensor used in the study was the PA2999.006NL, which has now been replaced with the improved PA3202NL. The coil winding technique is implemented in this highly automatable, low-cost standard product which is lightweight and, due to the Rogowski coil as a voltage source, is a zero power-consumption device with a stable voltage over a wide temperature range. The Pulse current sensor was developed as an alternative to the current transformer typically used in metering applications.

The STPMxx is a family of energy metering ASSPs (application specific standard products) designed to address a wide range of electricity metering requirements thanks to built-in features including signal conditioning, signal processing, data conversion, input/output signals, and voltage reference. These devices are designed for effective measurement of active, reactive, and apparent energy in a single- or poly-phase system using Rogowski coil-based sensors, current transformers, or shunt sensors, and can be implemented as a single-chip energy meter or as a peripheral measurement system in a microcontroller-based energy meter.