Energy Management

Smart Meter, Data Logger and Software: Planning Your First Energy Monitoring System

An energy monitoring system has three parts that must work together. Here is how they connect, where to put the meters, and what to settle before installation.

Most first-time energy monitoring projects go wrong in the planning, not the hardware. Meters end up in the wrong places, nobody owns the data, or the readings cannot reach the software. A little planning up front avoids all three.

Illustration: data logger collecting data from meters and sending it to the cloud

Tap or click the diagram to enlarge it.

How It Fits Together

The Three Parts

Each part has one job. The system works only when all three do.

Smart meter

Measures electrical quantities such as power and energy at one point. Many industrial meters offer a serial RS-485 port using the Modbus protocol, or an Ethernet port.

Data logger

Polls the meters over RS-485 or the network, adds time stamps, stores the readings and forwards them. It is the link between the field and the software.

Energy management software

Turns the readings into dashboards, trends and reports that people can act on.

Step 1

Where to Put the Meters

You do not need to meter everything. Start with the points that answer your biggest questions.

1
The main incoming supplyGives total consumption and the demand profile you can compare with the utility bill.
2
Large loadsCompressors, chillers, big motors and ovens are common big consumers. ISO 50001 calls the equipment and processes that use most of the energy significant energy uses — good candidates for sub-metering.
3
Production lines or areasLets you compare energy with output, for example energy per unit produced.
4
Solar generationIf you have rooftop solar, metering its output next to your consumption shows how much you actually use.

Step 2

Planning Checklist Before Installation

Settle these points before anyone orders hardware.

1
Get the single-line diagramIt shows where the feeders are and where meters and current transformers (CT) can physically fit.
2
List the metering points and CT sizesCheck cable sizes and available space, and whether existing meters can be reused instead of replaced.
3
Check communicationNote the distance of RS-485 cable runs, how many devices share one bus (often about 32 per segment, depending on the hardware), and what network is available for the logger.
4
Choose the reading intervalPick an interval that matches your question. For demand analysis, short intervals such as 15 minutes or less are common.
5
Decide who owns the dataName who looks at the dashboards, who can access them, and how the factory network is kept secure.

Avoid These

Common Mistakes

Metering everything at once instead of starting with the main supply and the largest loads.
Skipping a meter at the main incoming supply, so there is nothing to compare with the utility bill.
Not checking that the readings are correct after commissioning.
Installing the system without anyone responsible for looking at the data.

This article is general guidance. The right metering points, hardware and settings depend on a site survey and your electrical system, and are confirmed in a written design.

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