Precise Power Measurement and the Growing Demand for Data Centers

This article is published by EEPower as part of an exclusive digital content partnership with Bodo’s Power Systems.

Digitalization is advancing at an unprecedented pace, driving an exponential increase in data volumes. This surge is fueling the demand for data centers and expanding their role in data storage infrastructure. At the forefront of this development are climate protection regulations and resource conservation, creating a dual challenge: increasing overall IT infrastructure performance while simultaneously enhancing energy efficiency. This challenge spans multiple levels, from the power supply of entire data centers and the distribution within individual halls to the server and component level, affecting both component manufacturers and data center operators. In this context, precise power measurement is becoming increasingly crucial to ensuring energy efficiency, operational reliability, and economic viability. To meet these demands, we offer suitable measurement devices and solutions tailored to the industry’s needs.

The latest reports indicate the demand for data centers will continue to rise in 2025. According to JLL Research, data center construction with a total connected load of 10 GW is expected to commence worldwide, with 7 GW already set to be completed within the year. As a result, there will be a tremendous need for energy generation, all while maintaining a strong commitment to global climate protection targets and resource conservation. While the debate over the sources of energy generation remains contentious, there is a clear consensus on the necessity of high energy efficiency in data centers. Let us take a closer look at this crucial aspect and examine the key application areas where precise power and energy measurement can help address the regulatory, economic, and environmental challenges associated with energy consumption in modern data centers.

Power Supplies and Uninterruptible Power Systems for Data Servers

Server power supplies, ranging from low to high power classes, play a decisive role in determining energy consumption, heat dissipation, and, ultimately, the operating costs of data centers. More compact designs continue to enable higher system density and increased reliability through redundant power supply units. As a result, data center operators are increasingly equipping their servers and facilities with power supplies that meet the highest energy efficiency standards. In the U.S., the Energy Star environmental certification mandates a minimum efficiency level for power supplies in certified servers, specifically requiring compliance with the 80 PLUS Silver certification.

Manufacturers of power supply systems are now challenged to develop and continuously innovate their power electronics, not only to meet but to exceed efficiency and power density requirements in order to maintain a competitive edge. As a result, there is strong industry interest in achieving even the 80 PLUS Titanium certification, which signifies peak efficiency of up to 96 % at 50 % load.

To address these measurement challenges, we offer tailored and user-optimized solutions with our LMG600 series precision power analyzers. These instruments are already being used in the development phase to evaluate, optimize, and ultimately specify the efficiency of power supply products. The primary focus is on measuring input and output power to determine efficiency across various load conditions. An exemplary measurement using our LMG641 power analyzer is illustrated in Figure 1.

Figure 1. Example efficiency measurement of a server power supply using the ZES ZIMMER LMG641 power analyzer. Image used courtesy of Bodo’s Power Systems [PDF]

To meet individual measurement requirements of each test object, including accuracy, analog bandwidth, sampling rate, and simultaneous narrow- and broadband measurement, our power analyzers offer various particularly specified measurement channels for, amongst other applications, precise efficiency measurement:

• LMG600  B-Channel for universal measurement applications: best power measurement accuracy of ±  (0.05  % of reading + 0.02 % of range) with 500 kHz bandwidth and 150 kS/s sampling rate
• LMG600  S-Channel for high-precision wideband and DC-optimized measurement: best power measurement accuracy of ± (0.015 % of reading + 0.01 % of range) with 10 MHz bandwidth and 1.21 MS/s sampling rate

Power analyzers from our LMG600 series can be modularly configured with the aforementioned measurement channels for single-phase and multi-phase measurements, enabling direct measurements of up to 32 Atrms and 1000 Vtrms. For extended measurement ranges, primarily for current measurement, our high-precision PCT series current transducers support measurements up to several 1000 Atrms and can be directly supplied by the power analyzer. This capability is particularly crucial for efficiency measurements of high-power power supplies as well as energy measurements of high-capacity UPS batteries, allowing the assessment of their capacity, stability, and efficiency in load bank tests.

Ensuring Data Server Compliance

Both at the union and national levels, governments have established legal energy efficiency targets, leading to the development of tailored standards and regulations that align with specific national requirements and sustainability goals. As a result, data centers and servers are obligated to operate as energy-efficient and climate-friendly as possible, ensuring regulatory compliance. For example, the European Union mandates an EU Declaration of Conformity for installed data servers, which includes compliance with electromagnetic compatibility standards (EN/IEC 61000-3) and prescribed methods for measuring and reporting energy consumption (EN 50564). Other countries have implemented equivalent energy efficiency standards for data centers, each tailored to their respective national conditions and sustainability objectives.

To achieve legal compliance and certification, reliable conformity testing is essential. As illustrated in Figure 2, we offer the LMG Test Suite PC-based test software as a complementary solution to our LMG600 power analyzers. This software enables data server manufacturers and system integrators to conduct preliminary compliance tests, assessing harmonic distortion, power factor, voltage fluctuations, energy consumption, and other required parameters in accordance with:

• EN/IEC 61000-3-2 / -12 (harmonic limits)
• EN/IEC 61000-3-3 / -11 (voltage fluctuations and flicker)
• IEC 62301 / EN 50564 (standby power consumption)

The power analyzers fully comply with standards for harmonic measurements (EN/IEC  61000-4-7) and flicker testing (EN/IEC 61000-4-15). Equivalent measurement requirements and instrumentation apply for certification bodies. In line with the previously mentioned B-/S-Channel, we also offer a dedicated measurement channel specifically designed for such compliance tests.

• LMG600  C-Channel for high-precision (compliance) measurements at 50/60  Hz: best power measurement accuracy of ± (0.03 % of reading + 0.01 % of range) with 10 kHz bandwidth and 150 kS/s sampling rate.

Figure 2. Compliance testing system of the LMG600 series with the LMG Test Suite PC software. Image used courtesy of Bodo’s Power Systems [PDF]

Optimizing System Energy Efficiency in Server Operations – SPECpower Benchmarking

Processing massive amounts of data as quickly and reliably as possible requires high computational performance, often involving multiple processors. Depending on CPU utilization, i.e., the number of computing operations performed, the server power supply operates at varying load levels, each with different efficiency characteristics. This results in an overall system energy efficiency dependent on computational load, typically expressed as performance per system watt. The server system’s energy efficiency varies based on how long it operates at different computational loads, affecting the performance-to-power ratio. The objective of data center managers is to ensure a continuously optimized energy-efficient operation of their installed server configurations. This is achieved by carefully selecting, optimizing, and verifying server hardware to achieve the best possible average performance-to-power ratio over time.

The Standard Performance Evaluation Corporation (SPEC), specifically the SPECpower Committee, has developed an industry-standard benchmark (SPECpower_ssj2008) to provide a structured methodology for measuring energy consumption and computational performance.

At the core of this benchmarking process is a power analyzer officially accepted and supported by SPEC, such as the LMG600 series from ZES ZIMMER. A representative measurement setup is illustrated in Figure 3 and Figure 4.

The LMG611 benchmark results can be used as a status quo assessment for reporting to national regulatory authorities. In Germany and at the European level, this applies particularly to the mandatory reporting of energy consumption to the Energy Efficiency Register for Data Centers. With the SPECpower benchmark and our LMG600 series power analyzers, data center operators have a proven measurement solution to meet these regulatory obligations effectively.

Figure 3. Exemplary measurement setup of a SPECpower benchmark using the LMG611. Image used courtesy of Bodo’s Power Systems [PDF]

Figure 4. Practical measurement setup of a SPECpower benchmark using the LMG611. Image used courtesy of Hetzner Online GmbH and Bodo’s Power Systems [PDF]

High-Efficiency Transformers – Minimizing Power Losses to Optimize PUE

Due to their predominantly non-linear loads, such as data servers, power distribution units (PDUs), and frequency inverters for ventilation and cooling systems, data centers pose significant challenges for transformers connected to the grid. Without optimized mitigation of the current harmonics, transformers experience higher apparent loading, which forces them to operate in a lower efficient range. This, in turn, negatively impacts Power Usage Effectiveness (PUE), a key metric for data center energy efficiency. Oversizing transformers is not a cost-effective solution, additionally leading to higher no-load losses. To address these issues, standards, and regulations such as DOE  2016 (U.S. Department of Energy) and the EU  Ecodesign  Directive Tier 2 (Europe) already mandate the use of high-efficiency transformers (e.g., those with amorphous cores and improved harmonic load class K-13). These transformers achieve efficiencies above 99.5 % in the 50 % - 75 % load range while simultaneously minimizing harmonic distortion. Such exceptionally low power losses place stringent demands on measurement equipment used for acceptance and type testing. Higher measurement uncertainties in no-load, short-circuit, and phase displacement measurements could risk non-compliance with these stringent industry standards.

High-precision power analyzers, such as our LMG671 with the A- or S-type measurement channel, provide the required power measurement accuracy, bandwidth, and harmonic analysis for transformer testing. Our analyzers’ measurement tolerance specification is not power factor dependent, guaranteeing reliable results. Additionally, a dedicated Process Signal Interface (PSI) allows for the connection of temperature sensors, enabling temperature drift compensation during transformer short-circuit testing (for copper loss determination) using the integrated script editor. Our high-precision current and voltage sensors, including PCT series current transducers and HST series high-voltage dividers, enable the extension of measurement ranges to power levels from several hundred kVA to multiple MVA.

Precise Power Measurement Is Key

Precise power measurement is a key factor in the sustainable optimization of energy efficiency in data centers and servers. With the growing demand for computing power and increasing regulatory requirements, optimizing overall and system energy consumption has become essential. Using measurement solutions with ZES ZIMMER LMG600 series power analyzers and its accessories, manufacturers and developers of power supplies, power distribution units, and high-efficiency transformers can verify and optimize their systems through precise power analysis. This ensures compliance with regulatory standards such as 80 PLUS, ENERGY STAR, DOE 2016, and the EU Ecodesign Directive while enhancing energy efficiency and system performance.

The SPECpower benchmark, combined with our power analyzers, enables a standardized evaluation of server efficiency. It supports data center operators in optimizing the energy-efficient operation of their server infrastructure while ensuring compliance with energy consumption reporting requirements.

The combination of the LMG600 series power analyzers and dedicated testing software, such as the LMG Test Suite, ensures adherence to energy efficiency standards. Ultimately, it contributes to minimizing the environmental footprint of data centers. In conclusion, precise power measurement is essential for ensuring data center operation in a sustainable, economically viable, and future-proof manner.

This article originally appeared in Bodo’s Power Systems [PDF] magazine.