Digital Integrator for Rogowski Coils

June 12, 2019

LEM, the market leader in the provision of innovative and high-quality solutions for measuring electrical parameters, introduces the AI-PMUL integrator to complete its flexible clip-around Rogowski coil offering. AI-PMUL is a versatile digital signal conditioner of Rogowski coils secondary signal which offers a wide range of standard analogue True RMS and instantaneous outputs.


The Rogowski coils output voltage is proportional to the derivative of primary current. An electrical integrator circuit is therefore necessary to convert this signal, so it is proportional to the value of the primary current. This integrator is an essential component in current measurement with a Rogowski coil, and the amplification stage architecture and implementation have a major impact on the sensor’s electrical performance such as linearity, phase-shift and frequency bandwidth.


With a linearity error below 0.1 percent and combined with LEM ART & ARU (coming soon) class 0.5 Rogowski coils, it offers a universal metering and monitoring solution with an exceptional measurement accuracy up to 5000 A.


The AI-PMUL integrator covers in one universal product all the ratings that are expected. The simple configuration and the clear status visible from the front fascia allow it to configure with ease. The setting of the current range, input sensitivity and output selection is made through a simple, reliable and error free system using ergonomic push buttons (x2) and visible bi-colour LED. A green LED is for current range and a red LED is for input sensitivity and output selection.


Users can select between 12 current ranges from 100 A to 5000 A, 6 Rogowski coil sensitivity from 22.5 to 120 mV/kA and 6 possible outputs (4 true RMS output: 0-20 mA, 4-20 mA, 0-5 V and 0-10 V and 2 instantaneous voltage outputs: 0-225 mV and 0-333 mV). A 1 A instantaneous output version is also foreseen soon.


Working over a temperature range from -25°C to +70°C and operating from a single supply voltage of +24V, AI-PMUL is offered in a very compact size (100x78x15 mm) to be mounted on a 35mm DIN rail.


For small current measurement and difficult conditions, an input SMA coaxial connector is proposed as an option. Specifically, for three-phase system up to 3x, AI-PMUL models can be stacked together with an optional connector to share a single power supply.