The EMU Professional II 3/100 LoRa is a three-phase, MID-approved energy meter that reports its readings over LoRaWAN. That is the whole point: you do not get a monitoring meter but a billing-grade meter whose data leaves the distribution board without a data cable. Tenants, cost centres and charging points can therefore be billed where nobody ever pulled a cable. This version adds an SMA socket for an external antenna to the internal one — the difference that decides, inside a sheet-metal cabinet, between a radio link and radio silence. It connects directly, without current transformers; in the board it occupies five modules. Built by EMU Electronic in Baar, Switzerland.

• 100 Adirect connection, no transformers
• MID B + Dbilling-grade
• Class B1 % active energy
• over 3 yearsload profile at 15-minute intervals
• SMAsocket for an external antenna

What sets the Professional II LoRa apart

• Billing, not just watching: MID approval B + D is the difference between a meter that shows you something and one whose readings you are allowed to invoice against. Anyone billing tenants for electricity or charging internal cost centres needs exactly that — a measuring device without approval will not do, however accurately it measures.
• The external antenna is the reason this version exists: a sheet-metal distribution board is a Faraday cage. The internal antenna is enough in a plastic board or with the door open, but often not in a closed steel cabinet. Through the SMA socket you put the antenna where it has a view — outside the cabinet or in the room. That is what separates it from the sister version without the socket.
• The meter is its own archive: the load profile memory holds the main readings at 15-minute intervals for over three years, and does so to PTB-A 50.7. If the radio link drops for a week, nothing is missing afterwards; the data is in the device. For billing that depends on unbroken series, that matters more than any data rate.
• Class C: reachable at any time: the meter listens continuously instead of only briefly after transmitting. Configuration changes and queries therefore take effect immediately, not at the next uplink. Where the network does not carry class C, it continues as a class A device.
• You decide what gets sent: the interval and content of the uplinks are freely configurable. A meter that only delivers the index for the monthly invoice transmits differently from one feeding a load profile — the same device does both.
• Two directions kept apart: import and export are counted separately. With a photovoltaic system that is the precondition for separating third-party quantities — without separate registers, self-consumption cannot be cleanly told apart from feed-in.
• The clock sets itself: time synchronisation runs over the LoRa network. On a meter whose timestamped values feed into billing, a drifting clock is not a cosmetic flaw but a data problem.
• Decoders are ready: decoders and encoders are lodged with The Things Network and freely available for other systems. Integration therefore starts with finished readings, not with byte analysis.
• Two routes alongside: a volt-free S0 pulse output and the optical D0 interface to EN 62056-21 are there as well. The S0 output is the fallback if the radio link cannot be established — and the reading interface remains available independently.
• Readable without tools: the backlit graphic LCD shows readings, configuration and the state of the LoRa link directly on the device. Anyone standing in the basement wanting to know whether the meter is on the network does not need the dashboard.
• Data survives the power: the register values sit in EEPROM without voltage, for at least ten years. The internal clock bridges up to 18 days without supply.
• Swiss manufacture: developed and built by EMU Electronic in Baar. Housing of halogen-free, recyclable polycarbonate.

Where it is used

• Tenant electricity and self-consumption communities: the main case in Switzerland. Every unit gets its meter, the readings come together by radio — without pulling a data cable to the stairwell for each measuring point.
• Cost-centre billing in business: halls, departments or individual machines recorded separately and charged internally. MID approval makes the figures hard to argue with.
• Separating third-party quantities in self-generation: anyone generating electricity and passing it on must prove which quantity went where. Bidirectional metering provides the basis.
• Charging infrastructure: bill charging points individually, including in underground car parks where a network connection would be costly.
• Energy management to ISO 50001: consumption transparency as the basis for measures and their evidence.
• Sub-metering in existing buildings: retrofitting without a cable route — the most common reason radio wins here rather than Modbus.
• Rollouts across properties: one meter type across many buildings, read centrally. Because installation and connection need no wiring, it scales from one building to an entire portfolio.

That settles the selection. What follows is the depth for planning and integration.

What MID approval means in practice

MID stands for the European Measuring Instruments Directive; B + D denotes the conformity procedure: type examination by a notified body plus supervised manufacture. For you this means the readings of this meter are fit to be the basis of an invoice between two parties — without you having to prove measuring accuracy in a dispute. A device without approval can achieve the same accuracy and still be unusable for billing. The difference lies not in the technology but in the legal framework.

Accuracy class B to EN 50470-3 means a permissible deviation of one per cent on active energy. For reactive energy, class 2 to EN 62053 applies, so two per cent — reactive energy is not part of the MID in approval terms and is measured by the meter but not certified in the same way. The meter additionally carries PTB approvals 20.1 and 50.7; the latter covers the calibration-law-compliant load profile memory.

On calibration validity: in Switzerland, electricity measuring instruments are subject to mandatory calibration, and the period of validity is limited. Plan meter replacement as a recurring item, not a one-off installation — this is exactly what the choice between direct and transformer connection in the box above hangs on. This assessment comes from practical application and is to be understood as a selection aid, not as legal advice; the binding information comes from the Federal Institute of Metrology.

Radio inside the cabinet — what matters

The most common cause of a poor link is not the distance to the gateway but the cabinet itself. A steel sheet board attenuates the 868 MHz signal so strongly that a meter three metres from the gateway fares worse than one with a clear view over two hundred metres. That is exactly what this version is for: the antenna moves outside through the SMA socket.

What has proven itself is an antenna led out of the cabinet and mounted as high and as clear as possible — not against the inner wall and not right next to contactors or frequency converters, whose interference degrades reception further. With several meters in the same distribution, a radio test at the least favourable point is worthwhile before twenty devices are installed. Transmit power is 14 dBm, that is the regulatory maximum of the band — there is nothing to gain there; the improvement comes solely from antenna position and gateway location.

One point of orientation: the meter is mains powered. Transmit frequency therefore costs no battery here, only airtime. The legal limit on transmission duration still applies — anyone sending a full measurement packet every five minutes should keep an eye on it, especially where many devices transmit from the same place.

Operating effort

No battery, no maintenance cycle in the usual sense — the effort lies in self-consumption and in replacing the meter when calibration validity expires.

For project planning this means: running operation costs nothing beyond self-consumption, and that is unavoidable on a device of this class. The predictable item is the replacement — and whether it requires a shutdown is decided by the choice between direct and transformer connection.

Integration

The meter joins the network by OTAA or ABP; OTAA is set at the factory. The DevEUI begins with 102CEF, the AppEUI is 10 2C EF 00 00 00 00 00, and both, along with the AppKey, can be read directly on the display — commissioning needs no tool and no software, only the two buttons on the device.

For the payload, decoders and encoders are lodged with The Things Network and freely available from the manufacturer. Which readings appear in the uplink is up to you: active energy in both directions, active power, current, voltage and power factor per phase, plus the mains frequency. The meter writes the same quantities into its internal load profile memory, so a radio gap can be filled in later.

Because the device works as class C, downlinks are possible at any time — interval and content can therefore be changed in service, without sending anyone to the basement. Operation is possible both on public networks such as Swisscom, LORIOT and The Things Network and on a network you run yourself.

Versions

We stock the version with direct connection and an external antenna socket. We gladly source the remaining versions of the Professional II family on request.

Technical data

The general product data — protection rating, dimensions, weight, housing, temperature range, manufacturer part number and origin — is in the detail table further down this page.

Installation and commissioning

The meter clips onto the 35 mm DIN rail and occupies five modules, that is 90 mm. It is position independent, so it can also be fitted in a rotated distribution. For front-panel mounting there is a frame. The terminals take cross-sections from 1.5 to 35 mm²; the tightening torque is 2 Nm and must not exceed 3 Nm — on meters of this size, over-tightened terminals are a more frequent source of faults than loose ones.

After switching on, the display shows the state of the LoRa link. That is the moment at which it is decided whether the antenna position works — and the only convenient time to change it. Check reception before the board is closed and the cover fitted, not afterwards from the office.

Installation is reserved for a qualified electrician. For the transformer version the following also applies: current transformers must never be operated open-circuit, as dangerously high voltages can arise.

Scope of delivery

• EMU Professional II 3/100 LoRa energy meter with internal antenna and SMA socket, part number P20A000LE
• No external antenna. The socket is there, the antenna is ordered separately — see below.

Matching accessories

• Antenna with an SMA male plug: for an ordinary installation an 868 MHz antenna with 3 dBi is enough. If space in the cabinet is tight, the right-angled 90° version fits better, because it does not stand straight up against the lid.
• Leading the antenna out of the cabinet: that is exactly what this meter version is for. Either take the antenna with a 3 m extension cable, or combine a short antenna with an SMA extension in 20 cm, 1 m or 5 m. Every metre of cable costs a little signal — take the shortest length that gets the antenna out of the metal.
• Gateway, if no network is available: for indoor use the RAK7268CV2 WisGate Edge Lite 2+ is our best-selling device. For sites where the antenna has to go outside, the WisGate Edge Prime RAK7240CV2.

Help with sizing

The datasheet and manual are under the Documents tab at the top of this page. Unsure whether the direct connection is enough or the transformer version is the wiser choice, or how many gateways cover a property? Tell us how many measuring points and buildings are involved — the question of the right connection is gladly settled in conversation. And if it turns into a project — radio planning, pre-configuration in quantity or commissioning — we will gladly put together a quote.