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.


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.




Key Features Of Energy & Automation Transducers

• LEM make Energy and Automation transducers combine in a single case the most advanced AC & DC sensing technologies with signal conditioning electronic circuits (RMS or True RMS, threshold detection, etc).
• These Integrated transducers feature a switch or relay type output or an electrically isolated standard signal (0-5VDC, 0-10VDC or 4-20mA) that can be directly handled by any PLC or monitoring device.
• Energy and Automation demand complex adjustment and calibration operations and thereby manufacturers can benefit from the LEM technology and manufacturing know-how to achieve the highest performance and quality level of the market.

SELECTION CHART

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

Applications of Automation Transducers for different end user profiles

• Machine and Panel Builders
• System Integrators/ Engineering
• Factory Maintenance and Safety Services
• Energy Service Companies and Facility Management

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.

LEM integrated transducers are at the heart of many state of the art industrial supervision and automation solutions:

• Safety operations and personnel protection
  • Personnel protection may be achieved by installing a ground fault detection sensor on the power lead.
  • Maintaining safety lights on chimneys, towers and airports runways, among others, requires permanent monitoring. Measuring the current fluctuations at the control panel is much easier to implement and more reliable than the traditional method based on photocells.
• Process control (supervision and automation)
  • Monitoring the current of industrial electrical heaters in an injection die moulding machine to ensure product quality
  • In electric dip coating systems used in the automotive industry, measuring the anode current to ensure an even thickness of coating and to define the chemical quality of the dipping paint during production.
  • Measuring current during electroplating processes in the treatment of metal surfaces.
  • Measuring the current consumption of a smelting furnace in the glass industry in order to provide specific temperature gradients over a long period.
  • Monitoring current in the chemical industry in the manufacture of chemical raw materials by the application of electrolysis.
• Maintenance operations (condition monitoring)
  • It is possible to detect whether an electric pump’s performance is deteriorating (e.g. pump jam and suction loss) before it overheats or blocks.
  • An indication that a tool, e.g. a cutting tool is blunt and should be sharpened or replaced avoids early (and cost-ineffective) replacement, quality issues and even damages. This indication can be obtained by installing a current transducer on the tool to determine when the motor is drawing too much current.
• Facilities & infrastructures management
  • In heating, ventilation and air-conditioning applications or in high-pressure air systems, the amount of contamination on an air filter can be determined at an early stage from the level of current consumed by the fan’s electric drive.
  • Battery health is monitored by measuring charge and discharge currents (up to 200A) and leakage current (up to 10mA) in large installations such as data warehouses and telecoms.
  • The cathodic protection current is measured to monitor the effectiveness of corrosion protection equipment of concrete structures built with steel reinforced, bridges, pipelines or high voltage electricity pylon.
  • Measuring the current consumption of worm gear drives used to convey materials in biogas generation plants prevents blockages from occurring.
• Energy production and consumption
  • Monitoring DC power supplies or solar panels.
  • The electric drive for the rotor blade offset in wind power plants is monitored to ensure operational safety
  • Site energy sub-metering allows improving the efficiency in the usage of energy and reducing the electricity bill as well as the environmental impacts.