Enertex® KNX SmartMeter

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The most powerful energy meter with network analysis functions for the KNX bus.

The KNX SmartMeter (4 SU DIN rail) is a bidirectional meter for measuring the active and reactive power or energy, as well for power quality analysis. The measurement will be done in three-phase system or in three separate single-phase systems with the accuracy of class 1 (1%).

In the accuracy class 1 according to EN 62053-11 only accuracy requirements for the measuring range between 2% and 100% of rated current are determined. For smaller currents no requirements are defined, as these can not be accurately detected with conventional current transformers. In contrast, the Enertex KNX SmartMeter uses special high precision current sensors (Rogowski coils), which are calibrated to the device in factory. Thus, very small currents to 0.002% of rated current are accurately measurable. In addition, the current is measured with very little loss (< 2 mW loss). The provided current sensors may be installed directly at the main supply point of the grid. The SmartMeter is powered exclusively via the bus. Therefore, the device can even be operated if there is no voltage at the voltage inputs or the voltage has been separated.

The SmartMeter is available with two current sensor variants for different measurement ranges. A varaint with through-hole sensors for currents up to 85 A per phase (for power measurements from 0.5 W to 58,650 W) and another variant with flexible current sensors for currents up to 630 A per phase (for power measurements from 7.5 W to 293 kW) , which can be opened for easier mounting. All measured values (current, voltage, active power, reactive power, active energy, reactive energy, power factor, THD-U, THD-I, power harmonics, unbalanced load, zero current, power frequency) are shown on the KNX bus. All energy and measurement values are further stored as text data with a time stamp on a SD-card for further data analysis.

Besides specialized functions for performance-based load control, optimization of the own energy demand with photovoltaic facilities, calculating the usage or feeding charge with tariff switching the ETS application also provides various monitoring functions. In case of exceed of limits these functions report events as power outages, high voltage spikes, high power distortion, high reactive energy, highly non-uniform loading of the three phases (unbalanced load) or high neutral loading on the bus. To assess the power quality harmonics up to the 50th harmonic of current and voltage are measured. The numerous monitoring features enable fast accurate analysis of network-related failures, malfunctions and damages of electrical equipment.

The variants KNX SmartMeter 85 RT and KNX SmartMeter 630A can also be operated without KNX bus. Therefore a 24 VDC power supply must be connected to the KNX terminal. In this mode all measurement data without the harmonics are recorded every minute on the SD card. Recording moment for each measurement is then selected due to an internal battery-buffered clock that (UTC/GMT+ 1 hour) is set to the local time of Berlin at the factory and deviates one minute at maximum per year from the time of day. If required the clock can be adjusted using the SD card.