Electrical Distribution System in a Data Center

There are many different loads in the data center, such as IT devices, air conditioners (CRAC Units), pumps, lighting, etc. The critical supply from the utility / transformer / generator to the load is enabled by various types of power equipment. We are going to illustrate these equipment that are critical and without which it would not be possible to operate the data center.

Figure 1 is a block diagram of an electrical distribution system showing the name and the typical location of the electrical distribution equipment in a data center and the power flow path (Uptime Institute Tier Level II, N+1 Design) . This diagram is only an example of an electrical architecture and attempts to include all the possible major types of equipment used and their typical location in a data center. In the real world, a typical data center electrical design has much more complexity and diversity than that in this diagram.

Uptime Institute Tier II, N+1 Design

Figure 1 

Uptime Institute Tier III Design

Uptime Institute Tier IV, 2N+1 Design

Tracing the flow of power along its path (starting from the utility to the IT load) in the figure 1 above. It shows 8 essential facilities are critical for the power supply. This facilities distribute power to the downstream loads and also protect the power distribution system in the data center:

• Medium-voltage switchgear
• MV/LV transformer
• Low-voltage switchgear / switchboard / automatic transfer switch (ATS)
• UPS system with input/output switchboard and UPS distribution switchboard
• Power distribution Units (PDUs) and remote power panels (RPPs)
• Busway
• Panelboard
• Rack PDUs (rPDUs) / outlet strips

All facilities above, except for rack PDUs (rPDUs), are considered to be assemblies containing circuit breakers, switches, various types of relays, buses and connections, and control and auxiliary devices. Each device is optimized for long life and ease of maintenance.

The IEC 61947 & IEC 62271, which specifies the HV and LV switchgear terminology, considers switchboard to be the same as switchgear. For some regions like, North American, switchgear and switchboard are specified differently by ANSI and UL standards.

About Us


SMA combines with professional Chartered Engineers (CEng) from the Institute of Engineering Technology (IET), the Chartered Institute of Building Services Engineers (CIBSE) and the Hong Kong Institution of Engineers (HKIE). Our engineers have more than 20 years experience in data center design & build, building services engineering and energy conservation in the private and public sectors.

The team prepares the engineers and IT personnel to face any challenges in data centers and critical facilities of any size, in any location. For other design considerations / topics in data center and critical infrastructure, please visit 


(1) Site Selection,
(2) Space Planning,
(3) Cooling,
(4) Redundancy,
(5) Fire Suppression,
(6) Meet Me Rooms,
(7) UPS Selection,
(8) Raised Floor,
(9) Code & Standards,
(10) Transformers and Harmonic Distortion,
(11) Multi-mode UPS Systems,
(12) Electrical Rooms,
(13) Generator Systems,
(14) Generator Fuel Systems,
(15) Battery Systems,
(16) Earthing / Grounding and Bonding, etc.

Invitation to Data Center Technical Visit (2 Sites) + CPD Course in Critical Facilities and Data Center Design

2-days CPD Course in Data Center Facilities Design and Infrastructure Engineering (23 - 24 October 2014)

(HKIE CPD Course Code: CPD1029)

The course is designed for Building Services Engineers, Facilities / Data Center Managers, IT Management, etc. to enrich and update the knowledge in critical facilities and data centers design & build. It is more than a general introductory program for data center. Topics include:

- IT strategy
- Cabinet layout
- Raised floor system

- Data center network and structure
- Telecommunication backbones, redundancy, sizing and planning
- Fiber and optical system design
- Fiber and optical cable components
- Copper cabling components
- Copper system design and high speed ethernet
- Cable distribution, layout and management
- Earthing / grounding and bounding

- Power (1) – high / low voltage system, switch system, etc.

- Power (2) – UPS, transformers, fuel tanks, generators, etc.

- Cooling (1) – cooling topology, hot / cold aisle, etc.

- Cooling (2) – chiller, CRAC, cooling towers, etc.

- Environmental management system
- Physical security
- Fire protection system

Date: 23 - 24 October 2014 (Thursday - Friday)

Time: 10:00 – 18:00 (14 Hours)

Venue: 20/F, New Victory House, 93 - 103 Wing Lok Street, Sheung Wan, Hong Kong

(Very Near Exit A2, Sheung Wan MTR Station)

Fee: Special rate for HKIE's all membership classes

For details and syllabus, please refer to the CPD Course Calendar of Hong Kong Institution of Engineers, HKIE (http://www.hkie.org.hk/eng/html/cpd/cpdviewer.asp?sn=3248).

Kindly complete and return an Application Form together with a crossed cheque made payable to “Strategic Media Asia Limited” - Room 1605, 16/F, Causeway Bay Plaza 1, 489 Hennessy Road, Causeway Bay, Hong Kong.

Half Day Technical Visit to Data Centers in Kwai Chung and Tseung Kwan O (8 October 2014)

Sponsored by IXTech (www.hkcix.com) and HKCOLO (www.hkcolo.net)

Further to the critical facilities course, a half-day technical visit is targeted to provide an interactive environment and opportunities for members of IDC industry to exchange professional views and experience on TWO data center facilities (Tier II and Tier III+) and services. 

Date: 8 October 2014 (Wednesday)
Duration: 13:45 - 18:00
Assembly Time: 13:45 - 14:00
Assembly Point: Exit D, Kwai Fong MTR Station (Kwai Yan Road, Next to the Bus Stop)

Fee: HK$100, Round-trip transportation will be provided
(Waiver for the 2-day CPD course's participants)

For details of the technical visit, please visit 

http://www.stmedia-asia.com/data-center-tour.html.

Data Center Technical Visit

Again - Data Center Technical Visit

Sponsored by IXTech Limited

and Telehouse Hong Kong CCC (HKCOLO and KDDI Hong Kong)

We are pleased to announce that a Data Center Site Tour will serve for individuals who successfully attend our training seminars in Data Center Critical Facilities, Electrical and Air Conditioning System Design.

The Site Tour / Technical Visit targets to provide an interactive environment and opportunities for members of IDC industry to exchange professional views and experience on critical infrastructure and services.

It is also a rare chance to visit a world-class Tier III+ and a Tier II purpose-built data center facilities in Hong Kong during the same event.

For details, please visit the Site Tour Page and Rundown.

The Organizer

Strategic Media Asia (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE).

SMA is a critical infrastructure training, seminar and event organizer for corporations and professionals specialized in data center design & build, E&M facilities, structured cabling system, telecommunication, ICT and financial IT services.

For details of other data center courses and seminars, please visit our website at http://www.stmedia-asia.com/trainings.html.

Data Center Tier Levels and Uptime

The data center industry is laden with inter-related terms such as Uptime, Tier Levels, Availability, Redundancy and Reliability. In order to make an informed decision it is important to understand what they mean and what is the actual significance for any proposals you are considering in your analysis.

The concept of “Uptime” was pioneered by the Uptime Institute which was founded in 1993 and introduced its well defined Tier Classification system: I, II, III and IV, of which Tier IV represents the highest level of projected availability. Today, its Tier Certification system is globally recognized and its members are mostly Fortune 100-sized companies having multiple data centers averaging 50,000 square feet. And while not everyone subscribes to the Uptime Institute officially, marketing references to Tier 2,3 or 4 are common among those seeking to ascribe a certain level of design or construction to a data center’s overall availability or system redundancy, which may, or may not be totally accurate.

The terms “N, N+1 and 2N”, typically refer to the number of power and cooling components that comprise the entire data center infrastructure systems. Wherein “N” is the minimum rating of any component (such as a UPS, generator or cooling unit) required to support the critical load. An “N” system is not redundant at all, and the failure of any component will cause an outage, effectively describing a tier 1 type facility. N+1 and 2N, represent increasing levels of component redundancies and power paths, roughly mapping to the tiers 2-4, however it is important to understand that redundant components in themselves do not guarantee continuous availability, nor insure compliance with an Uptime Institute certified data center tier level.

Moreover, besides redundancy, the ability to do planned maintenance or emergency repairs on systems may involve the necessity to take them offline. This involves the key concept of “concurrent maintainability” which permits systems to be bypassed, without impacting the availability of the computing equipment. The Uptime Institute is well recognized in clearly defining concurrent maintainability in their Tier Level system. This is one of the key criteria in the design or certification of Tier III and Tier IV data centers.

Besides the level of infrastructure redundancy at the facility level, consistency of procedures for operations, maintenance and support of the critical infrastructure systems are key to ensuring continuous availability. Moreover, the Uptime Institute has now also established a related sub-category called Operational Sustainability to define and evaluate data center’s operational procedures, as an addition to their well recognized Tier Classification rating system.

Whether you chose to build or buy, you should examine all of these factors very closely to understand what is being promised if it is a brand new building and/or what the operating history of a proposed data center facility provider has been.


About Strategic Media Asia Limited

Strategic Media Asia (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE).

SMA, a critical infrastructure training and event organizer based in Hong Kong, provides an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on critical infrastructure and E&M facilities.

For details of other data center courses and seminars, please visit our website at http://www.stmedia-asia.com/trainings.html.