What had to be solved
The task was to make a measurement module that can be connected to a three-phase power system and provide safe, scaled analog signals for an external controller, test bench or dispatching system.
Projects / Measurements, sensors and data acquisition
Three-phase analog measurement front end
Analog front end for measuring three-phase voltage and current: isolated sensors, 12 V supply, and 0...3.3 V or optional +/-10 V outputs for PLC, SCADA or DAQ systems.
What the project reached
A module circuit and concept were prepared with voltage channels, current channels, isolated measurement transducers, internal power supplies and analog outputs for further processing by an external system.
Project materials
Photos and working materials
Engineering context
Important constraints
The inputs can be mains voltages and power currents, while the outputs must be safe controller-level signals.
The module has to isolate the power side from the low-voltage measurement system.
Different output ranges are useful when the same front end has to be connected to different upper-level systems.
Work done
What was included
Circuit design for a multi-channel voltage and current measurement module.
Selection of LV25-P isolated voltage sensors.
Selection of CKSR-15 current sensors.
Analog signal conditioning and scaling.
0...3.3 V and +/-10 V output options.
REF195 voltage reference.
12 V DC input supply with internal rails.
KiCad schematic preparation.
Details
Engineering project description
Purpose
The module takes over the dangerous and sensitive part of the task: measuring power quantities, providing galvanic isolation and scaling signals. The resulting analog signals can then be processed by an external system.
Measurement channels
The project covers phase-voltage and phase-current measurement, with an additional channel for neutral, PE or a separate branch. This makes the board useful for three-phase benches and electrical cabinets.
Integration
The outputs are intended for connection to a PLC, SCADA system, recorder or laboratory DAQ. Such a module is useful when the upper level does not have its own safe power front end.
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