Introduction to Data Centre Design

Transcription

1 Introduction to Data Centre Design Barry Elliott BSc RCDD MBA CEng Earthing, grounding and bonding November 09

2 Earthing what s the point Safety from electrical hazards Reliable signal reference within the entire information technology installation Satisfactory electromagnetic performance of the entire information technology installation

3 UK Applicable Standards BS 6701 Telecommunication cabling and equipment installations BS 7671 Requirements for electrical installations: IEE wiring regulations 16 th Edition Europe EN Application of equipotential bonding and earthing in buildings with information technology equipment EN Information technology Cabling installation Part 2 installation and planning practices inside buildings

4 Applicable Standards World IEC Electrical installations of buildings, various sections including; Part 5-548: Earthing arrangements and equipotential bonding for information technology equipment ISO 11801:2002 Information technology cabling for customer premises USA ANSI/TIA/EIA-J-STD-607 Commercial building grounding and bonding requirements for telecommunications IEEE STD Powering and Grounding Sensitive Electronic Equipment

5 Applicable Standards and. ETS Equipment engineering earthing and bonding of telecommunications equipment in telecommunication centres ITU-T K.27 Bonding configurations and earthing inside a telecommunications building ITU-T K.31 Bonding configurations and earthing of telecommunications installations inside a subscriber s building

6 Terminology Earthing The connection of the exposed conductive parts of an installation to the main earthing terminal of that installation (BS 7671) Equipotential bonding The electrical connection putting various exposed conductive parts and extraneous conductive parts at a substantially equal potential (EN ) Grounding (American) A conducting connection, whether intentional or accidental, between an electrical circuit and the earth. (TIA/EIA-607)

7 Bolting it all together the equipotential bonding system In an installation, main equipotential bonding conductors shall connect to the main earthing terminal extraneous conductive parts of that installation including the following: Water service pipes Gas service pipes Other service pipes and ducting Central heating and air conditioning systems Exposed metallic structural parts of the building The lightning protective system The metallic sheath of any telecommunications cable

8 Supplementary equipotential bonding conductors (where required) Exposed conductive parts Extraneous conductive part Circuit protective conductors Main equipotential bonding conductors Main earthing terminal Earthing conductor Main metallic water pipe

9 EN Application of equipotential bonding and earthing in buildings with information technology equipment

10 The frame ground grid shall be installed with a maximum cell size of 2 metres in each horizontal direction. The minimum cross-sectional area of the conductors that create the frame ground grid shall be 10 mm² min. The frame ground grid shall be connected to the earthing network at multiple points, where available. If the raised floor is installed with a surface that is intended to provide protection against electrostatic discharge, the DC resistance between the raised floor surface and the earthing grid shall be in the range 1 MΩ to 10 MΩ EN 50310

11 TIA 607

12 6.3 mm thick 101 mm high

13 Examples of Clean Earth Bar

14 Earth everything!

15 Earth everything!

16 Additionally, every sixth metallic raised floor pedestal needs to be bonded (to the SRG). This helps to bleed off static charges built up from the raised floor system. *EN suggest every 2 or 3 pedestals earthed with a 10 sq mm wire

17 Earthing system for computer room and entrance room

18 Underfloor TGB serving a row of racks

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20 TGB in Entrance Room

21 Signal Reference Grid - Purpose

22 Signal reference grid G TIA 942 Data center grounding infrastructure. IEEE Standard 1100 provides recommendations for the electrical design of bonding and grounding. Consideration should be given to installing a common bonding network (CBN) such as a signal reference structure as described in IEEE Standard 1100 for the bonding of telecommunications and computer equipment. If the system is on raised flooring, use a 2- foot x 2-foot (61-cm x 61-cm) grounding grid. (HP) Site preparation guide

23 SRG - Do we need one? Access (raised) flooring systems that utilize bolted stringer construction can be used to provide a simple SRG. Floor systems that have either no stringer or snap-in stringers do not provide for an effective SRG, and other methods for installing an SRG should be used. (IBM) system reference potential plane (SRPP) conductive solid plane, as an ideal goal in potential equalising, is approached in practice by horizontal or vertical meshes. The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical meshes may be interconnected to form a grid structure approximating to a Faraday cage, EN 50310

24 The high operating frequencies of modern computer equipment require that computer room products be supported both by a good equipment-grounding system and an effective signal reference grid. Compaq/HP A signal reference grid should be designed for the computer room. This provides an equal potential plane of reference over a broad band of frequencies through the use of a network of low-impedance conductors installed throughout the facility. SUN

25 ETSI EN Signal reference Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions, e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by switching, short circuits and atmospheric discharges.

26 Critical equipment should be located and bonded to the SRG at more than 6 feet away from the building steel or other potential lightning paths. All interconnecting communications, data and power cables should lay on or very close to the SRG Bond the signal reference grid to each piece of electronic equipment and to any other electrical or mechanical equipment located on the signal reference grid. Bonding connections to the signal reference grid should be as short as practical with no sharp folds or bends. Flexible straps are preferred to the use of round conductors.

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29 IEEE 1100