Sree Swarna Gutta
Maximize Production Efficiency with High-end Power Measurement
Machine-friendly I/O hardware for high-end measurement technology continues to grow, optimizing power monitoring while eliminating harmonic distortion
Over the past decade, power measurement technology has continued to advance and add an incredible number of options for controls engineers. One of the most exciting advances is that black box technologies are no longer the only options for power monitoring. High-end measurement solutions now exist as extensions of standard machine control platforms, and system-integrated I/O terminals not only gather data to be analyzed in the cloud or on a local PC, but also perform some power analysis on the hardware.
New high-end measurement I/O modules from Beckhoff provide cost-effective options to enhance each of the main energy measurement categories, including power monitoring, power measurement and maintenance, generally speaking. Because these I/O solutions are open, they help plants expand the range of power measurement data that can be gathered and analyzed. Adding high-end power measurement technology to each machine and production line will allow engineers to optimize equipment performance, diagnose issues faster and complete predictive maintenance just as irregularities begin to occur, which increases plant uptime, efficiency and profitability.
EtherCAT-enabled I/O modules for power monitoring offer sampling rates at a resolution of 50 µs, which is capable of monitoring any dynamic system. These solutions also simplify power monitoring by providing the instantaneous values of three-phase voltage up to 690 V AC or 400 V DC and currents up to 5 amps. High-end power monitoring is mainly used for grid analysis and monitoring incoming power, which is important in the wind industry, for example. On the other hand, high-end power measurement is often used at the machine level, and these modules can provide information necessary to correct harmonics in the power supply from the utility, which cause distortion and undesired results.
The combination of fast sample rates and application-specific capabilities leads to better, more actionable data insights. High-end power measurement modules help accomplish this through three key technologies along with the advantages of PC-based control platforms.
Distributed clocks, oversampling and timestamps
Like other EtherCAT devices, high-end power measurement modules rely on distributed clocks, oversampling and timestamps to provide high-precision data. These EtherCAT technologies work together to provide high sample rates with precise synchronization among all devices at less than 1µs.
The local clock in an EtherCAT device automatically and continuously synchronizes with all distributed clocks on a standard time base. This synchronization also compensates for different communication runtimes and minimizes the deviation between clocks to less than 100 nanoseconds. Distributed clocks enable the absolute minimum response time, deterministic actual value acquisition and deterministic set value output. Local clocks also trigger oversampling functions within these high-end modules.
With built-in oversampling functionality, the EtherCAT measurement modules transmit process data to the controller more than once per communication cycle. Because higher resolution requires reduced cycle times, oversampling enables repeated sampling of process data by a set factor within a communication cycle. This supports fast signal monitoring within a dynamic machine control system, signal sampling independent of cycle time and fast loop control, among other functions. Sampling rates of 200 kHz are possible, even with moderate communication cycle times.
Timestamp technology applies specific timestamps to process data in addition to user information. As a result, it is possible to pinpoint the exact moment when energy spikes and other important events occurred as well as trigger precise outputs independent of the cycle time. In addition to timestamping, distributed clocks and oversampling, different EtherCAT I/O modules can provide a variety of system-integrated diagnostics, filters, scaling features and form factors.
These technologies are even more effective when combined with PC-based control. When using an Industrial PC and automation software for machine control and monitoring, the process data acquired through high-end measurement modules can be further analyzed using existing software libraries on the machine. In addition, the data is transmitted easily from the local controller to the cloud using common communication protocols, such as MQTT, OPC UA or AMQP, to analyze further or compare the performance of individual machines against the entire line and plant. Further calculations can determine root-mean-square (RMS) values for voltage and current, minimum and maximum values and the harmonics in the system.
Better monitoring yields better performance
Relying on distributed clocks, oversampling and timestamps, high-end power measurement modules deliver significant benefits for machines and other applications. The modules feature zero crossing detection, with a precision of 1µs using the distributed clock technology. This makes it possible to execute switching operations at zero crossing with high-precision, which protects devices from in-rush current peaks.
These benefits present advantages in the case of harmonics, which can create undesirable results in machines. High-end power measurement modules conveniently integrate the evaluation of harmonics and total harmonic distortion (THD) of both voltages and currents. The modules can also detect current and voltage peaks, imbalances and residual current.
Implications of IoT
With all of the advances in IoT, low-cost maintenance modules can provide basic information about machines if high-end solutions are not needed. Not only do these entry-level options give voltage values, but also basic power quality analysis by means of the power quality factor.
For applications in which harmonics values are not an issue, the power quality factor can identify issues with the power supply in the system. This can also be very helpful in diagnosing issues, especially for interference-sensitive machines. Even machines that undergo extremely rigorous testing during commissioning sometimes encounter issues when shipped to the customer site. The problem might stem from power quality problems, which these modules can easily detect.
Cross-system communication challenges and the steep price point of previous black-box solutions created a barrier to performing such expansive power monitoring. However, newer modules are more affordable, and the openness of EtherCAT allows them to work in almost any system. The increased efficiency and production delivered by high-end measurement, along with the more affordable packages, gives the power for machine and plant optimization directly to the controls engineer.
Are you interested in enhancing your machine designs with high-end measurement? Contact your local Beckhoff sales engineer today.
Sree Swarna Gutta is the I/O Product Manager for Beckhoff Automation LLC.
A version of this article previously appeared in Control Engineering.