kWh meter iEM3155 - 63A Modbus MID A9MEM3155

Functional energy measurement in three-phase systems

The iEM3155 energy meter is an Acti9 series device designed for precise monitoring of electricity consumption in three-phase installations and networks with a neutral conductor. The device supports direct current measurement up to 63 A, eliminating the need for additional current transformers in typical residential applications and small industrial plants. With a width of only 90 mm (5 modules), the meter fits perfectly into modern modular switchboards, without taking up excessive space on the DIN rail.

A key advantage of this model is the MID (Measuring Instruments Directive) certification, which authorizes its use in sub-billing applications. This means that data on active and reactive energy consumption is legally reliable for settlements between building owners and tenants or between different units within a company. The device measures energy in four quadrants, allowing for precise tracking of both energy consumption and feedback – this function is particularly important in photovoltaic installations, where the meter must correctly register energy fed back into the grid.

Communication and data management

Modern energy management requires not only measurement but also easy access to data. This meter is equipped with a Modbus RTU interface (via RS485 port), enabling integration with building automation systems (BMS) and IoT monitoring software. Data is transmitted via screw terminals, which facilitates installation and reduces the risk of errors when connecting communication cables.

For local diagnostics and simpler control systems, the device features:

• D0 type pulse output – a programmable number of pulses (from 0 to 1000 imp/kWh or kvarh) allows for connecting simple external meters or alarm systems. *Programmable digital input – can be used for remote tariff switching or triggering alarm functions. *LED indicators – a green LED signals the presence of power, a yellow (flashing) LED informs about correct operation and measurement accuracy, and an additional LED indicates Modbus communication activity.

The device supports up to 4 tariff schedules, which can be configured internally or controlled by an external signal. This allows for precise settlement of consumption in different time zones (e.g., night/day tariff). The LCD display offers a clear preview of parameters such as phase and line-to-line voltage, current, and active and reactive power.

Application and operating conditions

The A9MEM3155 meter is designed for operation in networks with a frequency of 50 Hz or 60 Hz and rated voltages from 100 V to 277 V (phase to neutral) and from 173 V to 480 V (between phases). Accuracy class B for active energy according to the EN 50470-3 standard ensures the high level of precision required for professional metering applications.

The device is ideal where direct current measurement up to 63 A is needed without the use of transformers. The MID certificate makes it a legal tool for electricity billing, e.g., for rental settlements. Thanks to the Modbus RTU interface, it is easy to integrate with building management systems, gaining access to real-time consumption data. Multi-tariff capability allows for flexible cost settlement according to varied time rates, and the compact design occupies only 5 modules of width on the DIN rail, saving space in the switchboard.

The IP20 protection rating for the housing (IP40 for the front panel) means the device must be installed in enclosed switchboards protecting against access by unauthorized persons and larger solid particles. An operating temperature range from -25 °C to +60 °C enables installation in most technical rooms and unheated warehouse halls, provided adequate ventilation is maintained. Robust electrical connections are provided by screw terminals allowing for the connection of conductors with a cross-section up to 16 mm², which are resistant to vibrations and temperature changes.