High precision measurement of voltage and current
06 October 2011
The new EL3773 power monitoring terminal for the Beckhoff EtherCAT I/O system will monitor the condition of a three-phase ac or dc supply, collecting instantaneous values of power and voltage at a rate of up to 10,000S/s, and making them available to a supervisory controller for calculation or analysis. The input channels are transferred via oversampling; this results in the acquisition of actual values with a significantly higher resolution, in terms of time, than the communication cycle time.
The EtherCAT distributed clocks method is used in this system. These distributed clocks synchronise the EtherCAT devices precisely and independently of the PLC cycle. The EL3773 EtherCAT Terminal measures voltage and current via three channels in each case. The six channels are measured simultaneously based on the EtherCAT oversampling principle with a temporal resolution of up to 100µs. The maximum sampling frequency for each channel is 1kHz.
On the basis of the data supplied, it is possible with the aid of a PC to calculate true RMS values, power, power factors and frequency, and complex user-specific algorithms via the voltage and current curves. The fast sampling rate also enables the measurement of voltage and current peaks. Using the EL3773 power monitoring terminal, interference can be detected and corrected promptly in order to avoid damage to devices, increased electricity costs and downtime and to optimally boost the productivity of manufacturing facilities.
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