DATA CENTRES & CABLE MANAGEMENT
Meter, meter, meter, the key to energy optimisation
Using electrical power efficiently is fundamental to any data centre operator looking to reduce energy costs and meet sustainability goals. William Darby, managing director of Carlo Gavazzi UK explains how a robust metering strategy is the key to energy optimisation in a data centre
D
ata centres constitute a large and growing sector of energy use. They operate 24 hours a day, 365 days a
year, which means that even a small energy saving can have a significant impact when considered over a year. Inefficiencies in the power and cooling systems of the data centre infrastructure, for example, can provide data centre operators with opportunities for energy-efficiency measures. Taking advantage of such opportunities is often a cost- effective way to reduce running costs and can even improve data centre reliability. Meters provide the data that gives an insight into where and how much electricity is used in a data centre and on a more granular level, how much energy
is being used by individual systems and items of plant. Metering enables an operator to better understand how and where energy is being used and to help identify potential efficiency improvements and, ultimately, enable the results of these improvements to be measured. Metering also enables a data centre’s energy use to be benchmarked. There are numerous ways in which a data centre operator can have an impact on power consumption but without a baseline measurement it is difficult to know which initiatives are having the greatest impact. The old adage: you cannot manage what you cannot monitor, is as true for data centres as it is for any other power-consuming business, perhaps more so given the huge amounts of electrical power these facilities consume.
Power Usage Efficiency (PUE) is the industry metric used to determine a data centre’s energy efficiency. PUE is determined by dividing the total amount of power entering a data centre by the power used to run the IT equipment within it. PUE is expressed as a ratio, with overall efficiency improving as the quotient decreases toward 1.0. Data centre efficiencies are improving all the time as are the efficiencies of the IT servers and cooling systems. A data centre with a PUE of less than 1.2 would be considered highly energy efficient. To determine a data centre’s PUE an operator will need meter readings for the total power consumption of the data centre - both IT and non-IT loads such as cooling and lighting loads and the total IT load. Total power can be easily obtained
from the meter at the main power panel, where the electrical main supply enters the facility. In an existing data centre, meters can be sources of valuable, unexplored, information. If the meters are wired or wireless M-Bus type, gateways such as Carlo Gavazzi’s SIU-MBC can be used to convert data to the Modbus TCP/IP protocol, which can then be sent to a master to make this valuable information available as part of an automatic energy monitoring system. Or the EM271 multi-channel power analyser can be retro fitted which has Modbus RTU interface. For new facilities three phase smart power analysers, such as Carlo Gavazzi’s WM20, WM30 or WM40 can monitor electrical parameters such as harmonics, load operating hours in addition to providing power metering parameters such as voltage, current, power factor and frequency. Operators will also need to know the total power consumed by the IT equipment. Servers are
located in server racks, typically up to 48 servers per rack. These are positioned in rows to facilitate maintenance and to enable the racks to be cooled. A Power Distribution Unit (PDU) distributes the electrical power to the racks. Power monitoring of the IT hardware can be undertaken at PDU level with one meter serving each rack. A data centre can include hundreds of distribution panels. The innovative WM50 branch circuit monitoring system from Carlo Gavazzi was developed specifically for use in data centres after research showed a using traditional metering system for PDU would take up too much valuable space and require a significant amount of time to install. The WM50 is a complete solution for both new and retrofit data centre and critical load applications. While the base unit monitors the mains supply, its two branch buses link up to eight 12-channel split-core current transformer (CT) blocks. The system can therefore be scaled according to specific needs for up to 96 branch circuits in any combination of three-phase and single-phase loads or two-phase and single- phase loads. This approach reduces installation time by up to 75% when compared to existing solutions and affords a similar saving during commissioning. All data collected by the WM50 can be transmitted to the BMS or data centre monitoring system via either Modbus RTU or Modbus TCP/IP protocols. Using the WM50 to monitor power consumed by IT hardware, an operator can calculate a data centre’s PUE by dividing the total electrical power consumed by the total IT load. In addition to enabling an operator to calculate the operating efficiency of a data centre, monitoring power at PDU level will also give the operator a detailed, granular overview of IT power loads. This will help in ensuring loads are distributed evenly across the facility, which is why many data centres rely on PDU monitoring to improve efficiency and uptime.
Monitoring the power consumed at rack level using the WM50 will also allow a data centre manager to determine if the facility’s original assumptions for power allocations make sense under actual operation. Quite often, power is allocated to IT equipment on the basis of nameplate ratings which are conservatively high. This means more power, which may be required elsewhere in the facility, is allocated to an IT equipment rack than is necessary.
Combining the meters and sub meters with a monitoring gateway and controller, such as Carlo Gavazzi’s UWP 3.0 web-based monitoring system, will allow data to be exchanged locally or remotely to provide a complete energy management solution for both individual data centres and multi-site installations.
20 BUILDING SERVICES & ENVIRONMENTAL ENGINEER MARCH 2023 Read the latest at:
www.bsee.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
