IoT remote energy monitoring using LEM Split-Core CT (ATO) following theIEC 61869-2 Smart Grid standard
IoT Remote Energy Monitoring for the Smart Grid
IoT is perfectly suited for smart grid roll-out, thanks to the long range requirements and the small data
size needed for transmission. Using narrow-band RF, the standard for long-range communication, aninnovative remote energy monitoring solution is now possible. The solution consists of wireless energy
meters for the remote monitoring of electrical equipment with hardware, M2M connectivity (LORA,SIGFOX, 3G/GPRS…) and web services to manage the collected data (history, alerts, graphs,statistics, etc.). This IoT solution simplifies the implementation of the network and installation by theend-user, reduces infrastructure costs (no repeaters) and is typically compatible with existing solutions.
This approach is ideal for IoT due to the small power payload, the long range requirements and thesmall data size needed for transmission. The IoT star network configuration is typical for smart grid
deployment1

The typical application for energy monitoring is to identify energy consumption balance andoverconsumption analysis to pin point the areas to repair. Each wireless energy meter (1), using LEM
ATO (A) or LEM ART(B), is connected to the RF long range internet (2) and transmits (3) maintenancedata to a secure web server (4). End-users can follow equipment usage remotely (cycles, working time,consumption, etc.) or receive alerts when an anomaly is detected, such as loss of power or power peaks(5). The typical devices that have their energy measured are items with electrical motors, ventilators,pumps and compressors. The advantages of this solution are the simplicity of installation of the LEM
ATO or LEM ART, the connection over the internet, the real time measurements and the autonomy ofthe energy meter. The operating mode is RMS current acquisition of 1s every 10s and sends current
consumption statistics every 10 minutes or 15.
The advantages of IoT based Remote Energy Monitoring are:
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No need for deploying a local network infrastructure
Outdoor and indoor equipment monitoring
Wide area coverage
Very low energy consumption resulting in long lasting autonomous energy meters
Affordable and deployable with LEM ATO or LEM ART sensors

LEM ATO following IEC 61869-2
Split-core current transformers are not new, but conventional technologies used in these transformers
have presented numerous shortcomings - among these were solutions using either expensive materials
or providing poor performance. In this case, inaccuracy refers not to the readings themselves, but tothe linearity, the sustainability of a reading over time and the accuracy of the current compared to thevoltage (phase shift). The new Smart Grid IEC 61869-2 standard requires both accuracy AND phaseshift to be within Class 1.
The LEM split-core current transformer “ATO” with Ferrite dramatically improves the magnetic
permeability enabling such transformers to have high accuracy and excellent linearity even at very low
current levels following IEC 61869-2. The hardness of the solid material (consider Ferrite as a ceramic)
allows very fine machining, providing air gaps down to a few microns that are stable over many years.
Laminated materials such as FeSi or FeNi do not allow air gaps smaller than 20 or 30 microns, andthese are more sensitive to ageing and temperature changes. Add the small air gaps to the betterlinearity of the Ferrite at low magnetic excitation (i.e. for low current), and the Ferrite offers a better
performance than FeNi-80%, and at a lower cost.
Name

LEM ATOLEM ARTType

Split-Core Current Transformer

Flexible Rogowski CoilRange

10-125A

10-10000A

Material

FerriteWinding (no magnetic core)

IEC class

Class 1 and 3

Class 0.5

OutputInst Ma (1:1000), 225-333mV

22.5mV/kA

Diameter

10-16mm

35, 70, 125, 175, 200, 300 mm

IP class

IP 30

IP 572Conclusion

IoT based remote energy monitoring has an average amortization period of less than one year.
Maintenance operators spend 30% of their work time on the road and any repair needs usually two tothree trips, so this LEM solution saves time. Some sites or plant equipment are difficult to access (wasteof time and risk to the operator) and there is no way to add solid core transformers without a costly shutdown of the system. The LEM contactless split-core self-powered current transformer ATO can simply
be snapped over a cable, without the need to screw or weld on complex brackets, making installationand maintenance straightforward.
The IoT set-up combined with the IEC Smart Grid LEM ATO allows for immediate retrofitting of highperformance and cost-effective remote monitoring, energy metering and facility supervision systems.
About LEM
LEM is the market leader in providing innovative and high-quality solutions for measuring electricalparameters for a broad range of applications. LEM answers the demand for an accurate, reliable andeasy-to-install energy sensor for future Smart Cities.

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