Current and Voltage Transducers for energy management, process automation and control

There is an increasing number of process automation and condition monitoring applications where accurate measurement and precise control of electrical parameters are used in order to achieve the required level of safety, quality, reliability and operating efficiency. While measuring all kinds of AC and DC current and voltage signals, LEM current transducers and voltage transducers for automation also provide the signal conditioning to provide additional information required to ensure quick and reliable reaction.

These applications are related to different end-user profiles:

  • Machine and panel builders
  • System integrators / engineering
  • Factory maintenance and safety services
  • Energy service companies and facility management[/checklist]

LEM integrated transducers combine in a single case the most advanced sensing technologies and signal conditioning of electronic circuits (True RMS, industry standard outputs e.g. 0-5/10 V or 4-20 mA, active energy calculation, threshold detection, specific failure detection, etc.) in addition to integration of communication functions with PLC or monitoring device.


Model Current Rating Input Type Output Type Output Power Supply Case
AT Series 0-150 A AC 50/60 Hz Average 0-5V / 0-10 V Self powered Split Core
4-20 mA Loop powered Split Core
AP Series 0-400 A AC 30... 2kHz Average 0-5V / 0-10 V External +24 VDC DIN Split Core
4-20 mA Loop powered DIN Split Core
APR Series


0-400 A AC 30... 6kHz True RMS 0-5V / 0-10 V External +24 VDC DIN Split Core
4-20 mA Loop powered DIN Split Core
DHR Series 0-1000 A DC & AC 20...6kHz True RMS 0-5V / 0-10 V4-20mA External +24 VDC Solid Core
AHR Series 0-2000 A DC & AC 20...6kHz True RMS 0-5V / 0-10 V 4-20mA External +24 VDC Split Core
DK Series 0-200 A DC - 0-5V/0-10V 0-20mA/ 4-20mA External +24 VDC Solid Core/Split Core
DH Series 0-2000 A DC - 4-20 mA Loop Powered Split Core
HAZ Series 0-20000 A DC & AC 15...3 kHz True RMS 0-10V/0-20mA/4-20mA External ±15VDC Solid Core


Traditional process control still implies monitoring and regulation of parameters such as temperature, pressure, torque, position and others, but measuring these directly can be both inefficient and inaccurate. Measuring the input current of a load provides much more information than just the current value and has a number of advantages:

  • Speed – load changes are detected immediately, which can prevent equipment failure and avert process disruption.
  • Ease of use – a contact-less current transducer or switch can simply be snapped over a cable, without the need to screw or weld on complex brackets. Furthermore it can be installed in electrical control panels – thus avoiding complex wiring – to remotely monitor devices that often operate in harsh environments. In particular, since they are so easy to fit and put into operation, the self-powered split core current transducers can be retro-fitted into existing installations without shutting down operation.
  • Reliability – solid-state transducers are more robust than electromechanical devices and require no maintenance.
  • Savings – because costs are reduced through quick, easy installation and long-term dependability.
  • Safety operations and personnel protection
    • Ground fault detection
    • Maintaining safety lights
  • Process control (supervision and automation)
    • Electrical heaters in an injection die moulding machine
    • Electric dip coating systems used in the automotive industry
    • Electroplating processes
    • Smelting furnace in the glass industry
    • Manufacture of chemical raw materials by the application of electrolysis.
  • Maintenance operations (condition monitoring)
    • Electric pump’s performance
    • An indication that a tool, e.g. a cutting tool
  • Facilities & infrastructures management
    • Heating, ventilation and air-conditioning applications
    • Battery health
    • cathodic protection current
    • Worm gear drives used to convey materials
  • Energy production and consumption
    • Monitoring DC power supplies or solar panels.
    • The electric drive for the rotor blade offset in wind power plants
    • Site energy sub-metering

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