Measuring with EMU-1
The circuit breaker EMU-1 has three independent measuring channels. The input current I1 and input voltage U1 are measured continuously for energy calculations. The voltage U2 is measured in order to monitor the state of the switching transistors and the relay. In the special case of switched-off transistors and switched-on relay, U2 can determine if an external voltage is applied to the output terminals or not. Finally, the sum of the I1 and I2 currents are monitored. If the sum is greater than a configurable threshold an residual current-fault event can be triggered.
All three measurements are sampled seven thousand times per second (7kSPS). The sampling are done with a resolution of 24 bits by three sigma-delta (Σ-Δ) analog-digital converters. Sampling bandwidth is 1.2 kHz and the results are with an accuracy of at least 0.2% available for further processing in the system.
Any energy measurements like active power, reactive power, apparent power or cos φ are calculated from the measured input current & voltage. To achieve all the data continuously and in real time a DSP is used in EMU-1. In addition to complex mathematical calculations to determine all relevant energy data, the DSP provides additional valuable information such as zero crossings and peak values of the current and voltage or the mains frequency.
It goes without saying that the circuit breaker EMU-1 can act with all the calculated measurement results and its possibilities as a precision power meter with advanced features. All metering data can be easily retrieved from the user interface and so, reading metering data remotely is also a given option.
Usage of measurements
The measurement results from the DSP take two different paths in the system. Once the data is used by a µController to respond in real time to events such as over current or fault currents. On the other hand, all measurement results are transferred to the main processor in the system for storage and further processing.
The combination of instantaneous measurements in the DSP and the real time µController allows to implement notable functions, which never can be achieved by using normal line circuit breakers. Examples are the possibility to adjust the current value for the line protection, adjustable reaction times or adjustable duration of a fault before a reaction is executed.
How to buy EMU-1
This module will be available for purchasing by the end of year. If you are interested to get one device, you can register yourself to receive an offer as soon as the product is available.