Many energy-intensive companies have to go through a certification process in accordance with the ISO 50001 energy management standard and demonstrate continuous savings in order to continue receiving tax breaks on energy procurement. Retrofitting existing machinery with metering equipment is very difficult to accomplish on account of space restrictions. Installation in power distribution cabinets is one option. However, current solutions, which are mostly based on magnetoresistive metering technology, are relatively expensive and bulky, do not have integrated evaluation capability, and output readings in the form of interference-prone analog signals.
The metering system Fraunhofer IIS has developed together with an industrial user and marketer offers various unique selling points as a flexible monitoring system. It consists of bus-capable measurement sensors and an evaluation unit. All components are designed to save space and can be installed in existing distribution cabinets without having to shut down operation. Moreover, built-in voltage and current measurement simplify installation. Fitting the measurement sensor is a simple matter of clipping it onto the line that requires monitoring.
The measurement sensor is the core component of the system:
- PCB consists of a rigid part and a flexible conductor
- Flip chip assembly of sensors
- Plastic casing
- Conductor tapped via spindle
- Spring for long-term stability of connection
- VDE (Association for Electrical, Electronic & Information Technologies) certification
Voltage is measured by means of direct contact with the conductor during assembly. The voltage values are tapped via a spindle, then digitized and further processed using the analog-digital converter on the measurement sensor’s microcontroller. Highly integrated Hall sensors, which are arranged in a ring around the current-carrying conductor, perform the contactless current measurement. The individual measurement sensors are connected to an evaluation unit via bus cabling. The job of the evaluation unit is to amalgamate several sensors into a 3-phase measurement and to logically allocate the sensors to a machine or system. A higher-level automation or evaluation unit can instantly retrieve all machine-related readings via an Ethernet interface or a MODBUS RTU interface. In addition, the evaluation unit stores historical data in its internal flash memory. As a result, this data is available to peripheral devices for up to three days and can be accessed via the integrated FTP server.