While EMS is a three letter acronym with many meanings, for hExeis and our clients it is an Energy Management System.
What is an Energy Management System?
‘Manage’ stands at the center of EMS and at the most basic level we all know that before you can manage something, you need to be able to measure it. So the first thing an Energy Management System needs to provide, is the ability to measure energy, be it electrical, gas or thermal.
To have an EMS though, you need to have more than just the instruments to measure energy with. There must be a system, even if that is a manual system, of recording on a regular basis the readings from each instrument.
And you need to be able to take action based on the acquired data. So the System needs to provide ways of processing the data into information that can be acted on.
Is an EMS Software?
In a word, No. Software is not by itself an EMS.
Most Energy Management Systems do contain software to make it simple and automatic to collect the data and provide automated processing into actionable information. Examples are Schneider Electric’s Power Monitoring Expert product and KONSys’ AVReporter. Both are high quality EMS software packages we use and recommend.
So what is an Energy Management System then?
A typical EMS includes: sensing elements – Current Transformers (CT’s) in the case of electrical energy – energy meters, communications networks with gateways and a computer with a software product. This enables the system to collect, store, process, and provide information to the users about their energy as live data, reports, graphs, or dashboards.
Energy Meters include electricity, gas and thermal meters.
Electricity meters are by far the most numerous, complex, and feature-packed of the meter types. There is a very wide range of electricity meters with different accuracy levels, with or without communications and with a wide range of measurements. These can range from basic kilowatt hours to advanced waveform capture features for power quality analysis. Selecting the right meter for the job is important to ensure the right data is available for the minimum total outlay.
Gas and thermal meters on the other hand are typically less varied and provide fewer readings. They are however not necessarily simple devices, even though the data they provide seem basic in comparison to an electricity meter. A gas meter measures cubic meters of gas delivered. However, to translate this into an energy consumption, the meter must be configured with the energy value of the specific gas source, as well as being able to measure temperature and pressure to correct for these variables. Thermal meters have their quirks too, as temperature and flow rate are used to calculate thermal energy and the flow is a notoriously difficult variable to measure in turbulent liquids. Both gas and thermal meters typically provide their data as a pulse for each unit of flow and so pulse counters often need to be added to the System.
In an automated system it is essential that all the meters have communications ports and can be connected to a network of some form. Typically only high-end meters have an Ethernet network port the same as a desktop PC. The majority of meters instead support an industrial network known as RS485 (hardware layer) and a protocol (message format) known as Modbus, although there are proprietary protocols as well. This network is a low speed network that connects each meter in a daisy chain that can include 50 to 60 metering instruments on a single run of up to 600m in length. To connect these networks of meters to a conventional network requires a gateway, that can make the data available on an Ethernet network for an EMS software to collect. Gateways provide both hardware and protocol translation and may provide other features such as a web server and data logging.
At a most basic level, MS Excel is probably the most used EMS software in the world. Generic spread sheet products and methods aside, an EMS software, as part of an automatic system, needs to provide a feature set that is appropriately matched to the specific needs of the user. This will include logging of data for a sufficiently long period, to be able to make comparisons across relevant time periods be they seasons, semesters, batches or shifts. The software must also be able to process the data and present the resulting information. This is often done in tabular form on a screen, as printable reports, as dashboards or even as an alert or alarm.
EMS Software such as Schneider Electric’s PME and KONSys’ AV Reporter are available as on-premise solutions or can be hosted offsite at a data centre. There are also many Cloud providers of EMS software.
Overall, an EMS is a system and as such it needs to be well designed. For the system to work well and provide the decision support it is built for, all components need to integrate well and the components and total system need to be verified as working correctly individually and together.