New Industry Products

Digital Integrator for Rogowski Coils offers Range of Measurements

May 10, 2019 by Scott McMahan

LEM introduced the AI-PMUL integrator to complete its flexible clip-around Rogowski coil family. AI-PMUL is a versatile digital signal conditioner of Rogowski coils' secondary signal. It offers a wide range of standard analog true RMS and instantaneous outputs.

Applications for the AI-PMUL include transformer condition monitoring for MV/LV substations, current measurement for active power calculation; building sub-metering including energy efficiency monitoring, consumption analysis and cost allocation; power quality monitoring for electrical loads and distribution system equipment; fault detection, insulation and repair (FDIR) and insulating the site of the fault; remote terminal units (RTU).

The Rogowski coils' output voltage is proportional to the derivative of the primary current. An electrical integrator circuit is, therefore, needed to convert this signal. So, the integrator circuit is proportional to the value of the primary current.

This integrator is an crucial component in current measurement with a Rogowski coil, and the amplification stage architecture and implementation has an important impact on the sensor's electrical performance including phase shift, linearity, and frequency bandwidth.

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

In one universal product, the AI-PMUL integrator covers all of the expected ratings. The simple configuration and the clear status visible from the front fascia let it configure easily.

A simple, reliable and error-free system using ergonomic push buttons (x2) and visible bi-colour LED sets the current range, input sensitivity, and output selection. A green LED is for the current range, and a red LED is for input sensitivity and output selection.

Users can select among 12 current ranges from 100A to 5000A, 6 Rogowski coil sensitivities from 22.5mV/kA to 120mV/kA and among 6 possible outputs. These outputs include 4 true RMS outputs of 0mA to 20mA, 4mA to 20mA, 0V to 5V and 0V to 10V and 2 instantaneous voltage outputs 0mV to 225mV and 0mV to 333mV. A 1A instantaneous output version is also planned soon.

Operating from a single supply voltage of +24V and working over a temperature range from -25°C to +70°C, AI-PMUL comes in a compact size (100mm x 78mm x15mm) to be mounted on a 35mm DIN rail.

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

The CE marked AI-PMUL integrator series is covered by LEM's five-year warranty.


  • Accuracy Class 0.5 (IEC 61869-2)1
  • Linearity error ≤ 0.10%
  • Protection degree IP2X
  • DIN rail mounted 35mm
  • Push-in terminal
  • 4 selectable true RMS output signals: 0mA to 20mA, 4mA to 20mA, 0V to 5V, 0V to 10V
  • 2 selectable instantaneous output signals: 225mV, 333mV
  • 6 selectable sensitivities depending on Rogowski coil: 22.5mV/kA, 70mV/kA, 80mV/kA, 85mV/kA, 100mV/kA, 120mV/kA @ 50Hz
  • 12 selectable ranges: 100A, 200A, 300A, 400A, 500A, 600A, 800A, 1000A, 1500A, 2000A, 4000A, 5000A
  • Ambient operating temperature: −25°C to +70°C


  • Compact design for DIN rail assembly
  • High accuracy Class 0.5 (IEC 61869-2)1
  • Setup by user via Select / Edit buttons
  • Clear status via bi-color LED


  • Safety: IEC 61010-1: 2010
  • EMC: IEC 61326-1: 2012


  • Cross Power Plug-in: side contacts to stack up to 3 Integrator modules and use only one power supply.