Using Waveform Capture to Improve Power Quality Management

Jared Bosanko, Director of Sales U.S., Anord Mardix

In keeping with the principle you can’t manage what you don’t measure, power system data and analytics are a key component in any facility management toolkit to ensure stable performance and prevent downtime events. Going beyond simple power utilization tracking, today’s advanced metering solutions are expanding the range and type of metrics that DC operators can access easily. New types of multi-circuit monitoring systems (MCMS) are incorporating advanced data capabilities that can help maintain and prevent problems with critical power infrastructure.

One factor that distinguishes MCMS solutions is that they integrate not only upstream and downstream power utilization data but also incorporate additional analytics—such as harmonics and waveform analysis—that go beyond traditional metering approaches. An advanced MCMS approach makes use of the capabilities already built in to MCMS meters and then overlays sophisticated software and analytics on top to provide a robust view of the entire electrical landscape of a data center.

The Next Generation Metering Technology

Harmonics are unwanted currents or voltage distortions that are multiples of the fundamental line frequency. For example if the fundamental frequency is 60 hertz (Hz), which is typical in the United States, then 120Hz, 180Hz, 240Hz, and 300Hz are the 2nd-, 3rd-, 4th-, and 5th-order higher level harmonics, respectively. Excessive harmonic currents can overload wiring and transformers, creating heat and, in extreme cases, fire.

When an electrical anomaly occurs—such as a voltage sag or swell—tracking data can be used to identify the incident. For example, data can be plotted on a CBEMA/ITIC curve to assess the impact: voltage “overages of durations above the curve can damage equipment, and voltages and overages under the curve can cause operational issues.” However, plotting a curve has typically been a manual process that may only reveal issues long after the fact.

For real-time power quality monitoring, waveform capture offers immediate, actionable information. An advanced MCMS solution enables a facility to capture the waveform of the voltage and current flowing through a node at the instant the anomaly is detected and sync this information with the network clock.

Waveform Analysis Saves the Day

Waveform capture has proven essential to data center operators when analyzing any power quality issue. For example, one U.S. data center facility noticed an anomaly in their waveform data (see Figure 1). Upon analysis, engineers diagnosed that the cause of the waveform anomaly was most likely a breaker going out of phase. The facility maintenance team was able to swap out the breaker to restore system performance. If an overload had occurred on that breaker while its performance was degraded, it would have failed, potentially causing a downtime event.

Figure 1. Waveform capture graph generated from the Advanced MCMS monitoring system at a customer facility indicates that a breaker was experiencing some current anomalies likely due to faulty loads. The waveform capture provides evidence that this issue was load-based specific to this circuit and was not a result of poor power quality from the source. (Graph: Anord Mardix)

Similarly, a different North America-based facility was able to use waveform capture to spot a power spike on a single circuit. On further investigation, they tracked the spike to a specific rack where a power unit had failed. By catching the failure and replacing the unit quickly, they prevented this single unit failure from turning into a cascading failure as other units became overloaded and potentially taking down the entire rack.

Using an MCMS system with these advanced monitoring features can deliver an added level of reliability and power security to any data center.

Making Waveform Capture Available with Advanced MCMS

Some advanced MCMS systems on the market now can provide data center operators with an unprecedented level of visibility into power quality and performance by making high resolution waveform capture per circuit a standard feature down to the branch circuit level.

Typically a capability reserved for high-end, high-cost monitors, new advanced MCMS solutions incorporate harmonics, waveform capture, and other advanced and analysis features—at a more affordable cost. An MCMS system can automatically triggers waveform capture based on user-defined voltage and current thresholds and logs up to 32 GB of data locally. Seeing events graphically is easy using the integrated HTML interface or users can simply export the data over a network or by removing the onboard storage card.

Figure 2. Example of waveform capture reported in the Anord Mardix Advanced MCMS, which logs any voltage violations outside of CBEMA / ITIC power quality tolerances and plots them graphically on an HTML console as well as making them available as .CSV files over the network. (Graph: Anord Mardix)

In addition to waveform capture, some MCMS monitors can automatically capture and log any voltage violations that fall outside the CBEMA / ITIC power quality envelope (Figure 2). The most advanced systems classify each voltage event with a time stamp, event type (Voltage Swell, Voltage Sag, Dropout, Low Frequency Decaying Ringwave, High-Frequency Impulse, or Ringwave), category type (temporary or instantaneous), voltage level, and event duration.

Figure 3. Example of voltage event capture and analysis as reported in the Anord Mardix MCMS, classified with a time stamp, event type, category type, voltage level, and event duration. The high-powered CPU of the Anord Mardix MCMS monitor facilitates a voltage sampling rate over 40 kHz delivering the needed resolution for the microsecond data. (Graph: Anord Mardix)

Using an MCMS system with these advanced monitoring features can deliver an added level of reliability and power security to any data center by:

• Revealing event patterns not visible with conventional meters and exposing potential issues before they have a chance to affect critical loads.
• Maintain evidence of performance for SLAs
• Preserving critical incident data down to the branch circuit level simplifying root cause analysis
• Visualize effects of additional loads

To learn more about using waveform capture and MCMS, read the White Paper: Optimizing Data Center Power Management with Advanced Multi-Circuit Monitoring Systems.