Learn How to Design Electrical Systems for Mission-Critical Infrastructure (28 - 29 March 2019)

Course in Electrical Design for Mission Critical Supply (2-day)
(28 - 29 March 2019, approved CPD course by CIBSE UK)


Mission critical facilities have particular power requirements that significantly impact how they are designed and operated. You will gain insight into the critical supply system, from power components to distributions and efficiency; from power requirements to sizing, design, testing and commissioning:-


-- Concept on primary supply and secondary supply
-- Power flow in mission critical supply system
-- Features of major equipment for critical supply

    > Uninterrupted power supply and power storage
    > Backup generator
    > Automatic transfer switch
    > Static transfer switch
    > Isolation transformer

-- Efficiency assessment
-- Power quality review
-- Configuration diagram of critical supply (N+1 / 2N) design & analysis
-- Review of cable sizing to incorporate harmonics content
-- Earthing system design
-- Testing and commissioning requirements
-- Brief of Systems Merging Appraisal Test (SMAT)


The course details about the power system components that support typical data centers or mission-critical infrastructure. It prepares individual to fully understand the high voltage systems' design & build by exploring the international best practices and the instructors' experience.

All sections are conducted by Chartered Engineers (CEng) who have more than 20 years experience in electrical engineering, project management, sustainable engineering and facility engineering for critical services.


Date: 28 - 29 March 2019 (Thursday - Friday)
Time: 10:00 – 18:30
Venue: 19/F, New Victory House (Officeplus), 103 - 93 Wing Lok Street, Sheung Wan, Hong Kong
(Near Exit A2, Sheung Wan Station)


Fee: Special rate for (1) the HKIE / CIBSE or all professional membership classes in engineering; or
(2) more than 1 enrollment made at the same time


For course details, please refer to http://www.stmedia-asia.com/newsletter_6.html.



Enrollment & Registration

Kindly complete and return an Application Form together with a crossed cheque made payable to “Strategic Media Asia Limited” - Room 403, 4th Floor, Dominion Centre, 43 - 59 Queen's Road East, Hong Kong.


About the Organizer

Strategic Media Asia Limited (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE). Our mission is to provide an interactive environment and opportunities for the engineers to exchange professional views and experience on critical infrastructure and data center services.

SMA connects IT, Facilities and Design. For details, please visit www.stmedia-asia.com/about.html.


Adverse Weather Arrangement - Events in the morning, afternoon or evening will be cancelled if typhoon signal No. 8 or above or black rainstorm warning is still hoisted after (or is announced by the Hong Kong Observatory to be hoisted at / after) 6:00 a.m., 11:00 a.m. and 4:00 p.m. respectively. Delegates will be notified when the class will be made up as soon as possible.

Subscribe to the Knowledge Blog in Critical Infrastructure Design

RELIABILITY & REDUNDANCY MATTER - Your facilities and IT infrastructure are complex that are different from general buildings and require special design and operation knowledge and skill. Understanding the design considerations and avoiding costly downtime are critical.

Subscribe to our Knowledge Blog (http://green-data.blogspot.com or http://data-center-design.tumblr.com), share your view and get monthly readings online. All topics focus on key components and considerations of designing / operating mission-critical facilities and infrastructure:-

(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, etc.

P.S. Think your team might also be interested? Pass it on >

Strategic Media Asia Limited
Connecting IT, Facilities and Design

T (852) 2117 3893 | F (852) 2184 9978

Room 403, 4th Floor, Dominion Centre, 43 - 59 Queen's Road East, Hong Kong
http://www.stmedia-asia.com | http://green-data.blogspot.com

"Tier 3+" or "Tier 4-Ready" Data Centers?

This is usually found in some data center specifications: "Tier III+" or "Tier IV-Ready" *

Let's clarify: There is no such thing as "Tier III+" or "Tier IV-Ready" for large data centers. They are not granted by any organizations in data center / critical facilities like Uptime Institute or Telecommunications Industry Association (TIA) - ANSI/TIA-942 **.


* The latest TIER IV-Ready Certification by the Uptime Institute is designed for modular data centers which enjoy the same level of reliability and resiliency that they have in their larger data centers.

** The term ‘Tier’ was used in the ANSI/TIA-942 Standard until the ANSI/TIA-942: March-2014 edition. In the March 2014 edition the term ‘Tier’ has been replaced by either ‘Rated’ or ‘Rating’.


Recap (1) More about Data Center Tier Levels; and
(2) Data Center Tier Levels and Uptime


The Uptime Institute issues Tier Certificates (Constructed Facility and Design Documents) for data center infrastructure. When a data center is accredited as Tier III Constructed Facility, the infrastructure, at the time of the site visit and demonstrations, should be "Concurrently Maintainable" and N+1 (N means Utility Power) with 1 active + 1 alternate distribution paths (electrical power backbone) and 2 simultaneously active critical power distribution.

One of the major different between Tier III and Tier IV infrastructure is the requirement of Distribution Paths - Electrical Power Backbone. Tier IV facilities require 2N / 2N+1 which means 2 electrical power backbone should be simultaneously active. It is nearly double the infrastructure of Tier III.

Although the Uptime Institute Tier Standard or the TIA-942 Standard does not require dual feeds from different power companies to achieve Tier IV standard, is it worth to build a Tier IV data center in Hong Kong?

The situation is different. Electricity supply in Hong Kong is highly reliable, exceeding 99.999%. The two power companies, CLP and HK Electric have adequate capacity and backup in electricity generation and in the transmission and distribution networks, which assured robustness and reliability of supply. A number of high-tier data centers are being serves by two utility feeds from different substations of the same power company.

  

A Tier IV infrastructure is nearly double of the Tier III. Thus most of the large data centers in Hong Kong are usually Tier III but leave rooms / spaces for adding facilities and expansion if required in the future (ready / upgradable to Tier IV standard).


About us

SMA connects IT, Facilities and Design. For the other design considerations, 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, etc.

All topics focus on key components and provide technical advice and recommendations for designing a data center and critical facilities.

Strategic Media Asia (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE) UK. The team exists to provide an interactive environment and opportunities for members of ICT industry and facilities' engineers to exchange professional views and experience.

Critical Facilities & Data Center Design Consideration: Generator Systems Design (1)

Let's recap the basic concept of mission-critical facilities:-

(1) Uptime Four-Tier Levels
(2) Critical Supply Diagrams and Configurations

The terms “N, N+1 and 2N”, typically refer to the number of power supply and cooling components that comprise the entire data center infrastructure systems. An “N” system is not redundant at all. N+1 and 2N, represent increasing levels of component redundancies and power paths, roughly mapping to the Tiers 2-4.

A paralleled generator system uses two or multiple generators to form a large-capacity generator system. Paralleling multiple generators is achieved by synchronizing the output of the generators and connecting them to a paralleling switchgear (PSG) common bus. Synchronizing the output of the generators requires all of the paralleled generators to have the same voltage, frequency, and phase rotation.

With closed transition back to the utility, PSG will parallel the generators and synchronize the generator output with the utility source for a short duration before transitioning back to utility power. When connecting the generators in parallel or synchronizing with the utility, the following criteria must be met:

• Matched / proper frequency
• Matched / correct phase rotation
• Phase voltages in phase and within specified voltage range

Typical parameters that determine synchronization include a voltage difference of less than 5%, a frequency difference of less than 0.2 Hz, and a maximum phase angle of 5 electrical degrees between the sources.

Closed transition is used when it is desirable to transfer loads with zero interruption of power when conditions permit. It is used when the generator system transfers back to the utility and when load testing the generators with building loads. Closed transition can be either a soft load transfer or a make-before-break transfer. The PSG soft-load transfer synchronizes and operates the generators in parallel with the utility and transfers loads in increments between the two sources, thereby minimizing voltage or frequency transients on the generator plant and utility distribution system.

The typical soft-load-transfer overlap time is around 2 seconds. The make-before-break transfer will parallel the generators and perform a transfer of load from the generator to the utility. This can be the transfer of one large block load or the transfer of multiple block loads having time delays between the block loads. Time-delay transfer can either be programmed through the PSG or the downstream automatic transfer switches (ATS). Typical ATS make-before-break transition overlap time is usually less than 100 milliseconds.


To simplify the design of a paralleled generator system, identical generators should be used with the same manufacturer, ratings, type, output rating and alternator pitch.

If paralleling of dissimilar generators is required because of existing onsite conditions, the design of a paralleled generator system becomes much more complex. Each generator configuration must be evaluated and dissimilar components, such as speed control, voltage regulation, and alternator, must be retrofitted to match.

"Pitch" is the term used to define the mechanical design characteristics of the alternator. Paralleling a generator of 2/3-pitch alternator design with a generator of 5/6-pitch alternator design will result in circulating neutral currents. The circulating current will be disruptive to protective device operation and may damage alternators.


Configurations


The electrical loads must be classified into emergency loads, required standby loads, and/or optional standby loads that classified loads are separated, and the generator sets are sized so one generator can serve the emergency and required loads purpose.(see the following Figures)

One generator supplies emergency power to emergency loads, required standby loads and optional standby loads.

Multiple generators in parallel supply power to emergency loads,  required standby loads and optional standby loads.

Kindly note paralleled generator systems that rely on a single master control for signals to start and close to a paralleled bus actually replace one failure point with two, as the master control and the communication link between the master control and the generator systems each represent Single Points of Failure. A well-engineered paralleling system will have dual hot-backup control systems, redundant communication pathways, redundant best battery select dc power supplies, multiple breakers, multiple power pathways, and a well-documented procedure for system recovery whenever a component fails.

Benefits of Parallel Generator Systems


Paralleling multiple sources provides increased reliability, flexibility in load management, and maintenance capabilities with little to no disruption. Multiple generators paralleled to a common bus can better serve emergency and business critical loads, particularly for system response time and dynamic load response once in operation. However, more complex, parallel generator standby systems have significant advantages with respect to reliability and redundancy. These advantages include redundancy, efficiency and ease of maintenance and serviceability.

Redundancy: 

The redundancy inherent in the parallel operation of multiple generators provides greater reliability than a single generator unit for critical loads. If an N+1 configuration is adopted, one generator can be offline for maintenance while serving the required loads. Furthermore, providing a running spare, an N+1 generator configuration will increase the reliability of the generator system from 98% to 99.96% reliability.

Efficiency: 

Variations in power demand can cause a single larger generator to run at loads of less than 30% of capacity. The optimum operational point is between 75% and 80% of its rated value. The paralleling control system can be equipped with a generator load control that can add and remove generators in response to the actual load/demand of the system. If the load changes and demand reach 90% of running capacity, for example, an additional generator can be started, synchronized, and paralleled to the bus with no time delay.

Maintenance and Serviceability:

Maintenance can be performed without interrupting the availability of the generator system because one generator can be removed from the system to undergo scheduled or unplanned maintenance while the other generators are available to supply the loads.



Go to the next articles:
Generator Systems Design (2) - Generator Ratings
Generator Systems Design (3) - Generator Sizing


About us

Strategic Media Asia (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE) UK. The team exists to provide an interactive environment and opportunities for members of ICT industry and facilities' engineers to exchange professional views and experience.

SMA connects IT, Facilities and Design. For the other design considerations, 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, etc.

All topics focus on key components and provide technical advice and recommendations for designing a data center and critical facilities.

Keep Your Knowledge Current in Electrical Design for Mission Critical Supply

Within the built environment, mission critical facilities and data centers have particular power requirements that significantly impact how they are designed and operated. Further to the


(1) Site Selection,
(2) Space Planning,
(3) Cooling,
(4) Redundancy and
(5) Fire Suppression,


you are recommended to join the 2-day advanced learning (CIBSE approved CPD Course) in Electrical Design for Mission Critical Supply.

With more than 18 years experience in critical facilities and electrical system design, the Instructors (with Chartered Engineer (CEng) status) will detail about the international standards, best practices and design project experience. You will gain insight into the critical supply system, from power components to distributions and efficiency; from power requirements to sizing, design, testing and commissioning.


-- Concept on primary supply and secondary supply
-- Power flow in mission critical supply system
-- Features of major equipment for critical supply

  > Uninterrupted power supply and power storage
  > Backup generator
  > Automatic transfer switch
  > Static transfer switch
  > Isolation transformer

-- Efficiency assessment
-- Power quality review
-- Configuration diagram of critical supply (N+1 / 2N) design & analysis
-- Review of cable sizing to incorporate harmonics content
-- Earthing system design
-- Testing and commissioning requirements
-- Brief of Systems Merging Appraisal Test (SMAT)


This is an advanced learning section on top of the Data Center Facilities Design & Infrastructure Engineering. For details, please refer to http://www.stmedia-asia.com/newsletter_6.html.



About the Organizer

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

The team exits provide an interactive environment and opportunities for members of ICT industry and facilities' engineers to exchange professional views and experience.

SMA connects IT, Facilities and Design. For accreditation details and background, please visit www.stmedia-asia.com/about.html.

Further Learning in Electrical Design for Mission Critical Supply + Technical Visit to Power Quality Centre

Designing an electrical system for mission critical purpose or data center can be a real challenge. Further to a training section in Data Center Facilities Design and Infrastructure Engineering, an advanced unit - Electrical Design for Mission Critical Supply - is going to launch in December 17 - 18, 2015.

The 2-day electrical design course introduces the power system design that support typical data centers or critical facilities. It prepares individual to fully understand the mission critical supply system, from power components to distributions and efficiency; from power requirements to designed, testing, commissioning and maintenance.


Day 1

- Concept on primary supply and secondary supply
- Power flow in mission critical supply system
- Features of major equipment for critical supply

  (1) Uninterrupted power supply (UPS) and power storage
  (2) Backup generator
  (3) Automatic transfer switch
  (4) Static transfer switch
  (5) Isolation transformer

- Efficiency assessment
- Power quality review


Day 2

- Configuration diagram of critical supply (N+1 / 2N) design & analysis
- Review of cable sizing to incorporate harmonics content
- Earthing system design
- Testing and commissioning requirements
- Brief of Systems Merging Appraisal Test (SMAT)


Date: 17 - 18 December 2015 (Thursday - Friday)
Time: 10:00 – 17:30
Venue: 19/F, New Victory House (Officeplus), 93 - 103 Wing Lok Street, Sheung Wan, Hong Kong
Fee: Special rate for CIBSE / HKIE all membership classes


For details, please refer to http://www.stmedia-asia.com/newsletter_6.html.



Technical Visit to Hongkong Electric Power Quality Centre
and Smart Power Centre


Voltage dips and harmonics are two major issues affecting power quality. To share the knowledge, Hongkong Electric has established a Power Quality Centre which enables participants to understand more about power quality and the ways to safeguard the power supplies for their important services.

The Power Quality Centre is equipped with a voltage dip generator and different mock-up installations to demonstrate the effects of power quality on sensitive equipment, as well as the voltage dip ride-through solutions for various types of equipment.


The “Smart Power Centre” provides advice on the choice of electrical equipment or appliances as well as general knowledge on the safe and smart use of electricity. The centre mainly focuses on introducing the effectiveness and easy use of electrical appliances, intelligent panel and automatic lighting control.


Further to the critical facilities / electrical design courses, you are cordially invited to attend the technical visit / guided tour by the HK Electric:


Date: 8 January 2016 (Friday) *  (Full, updated on 21 December 2015)
Duration: 15:00 - 17:00 (2 hours)

Assembly Time: 14: 45 - 15:00
Assembly Point: G/F Lobby, Electric Centre, 28 City Garden Road, North Point, Hong Kong
(Next to the City Garden - Exit B, Fortress Hill Station)


* Pre-registration required
* Free admission for the technical visit
* Intake target: 15 - 20 participants
* Seats are limited. Priority will be given to the CPD course's participants


For the visit details, please refer to RUNDOWN.



Enrollment & Registration

Kindly complete and return an Application Form together with a crossed cheque made payable to “Strategic Media Asia Limited” - Room 403, 4th Floor, Dominion Centre, 43 - 59 Queen's Road East, Hong Kong.



About the organizer


Strategic Media Asia Ltd (SMA) is one of the Approved CPD Course Providers of the Chartered Institution of Building Services Engineers (CIBSE). SMA exists to provide an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on data center design, critical infrastructure system, electrical and mechanical facilities, etc.

SMA connects IT, Facilities and Design. For details, please visit our website at http://www.stmedia-asia.com/trainings.html.

Data Center Design Case Study

When the reliability demand is high and the data center has to work around pre-existing building constraints, there are significant design challenges.

With approximately 120,000 sq ft of white space divided into eight Tier III, 2 MW power data halls, the 20 MW data center meets a number of design challenges before construction even began.

The data center was originally the site of an old manufacturing facility. Coupled with the owner’s building requirements, this created a few challenges to the data center’s electrical distribution system design. Here’s a look at how Environmental Systems Design, working together with the other members of the building team, was able to solve them.


Challenge No. 1: The transformer


In an effort to maintain consistency across others data centers, the corporation likes to specify company-standard mechanical, electrical, plumbing (MEP), and fire protection equipment for all of its mission critical facilities. However, much of this equipment is designed for outdoor use, and because this particular facility has very limited outdoor space, significant adjustments had to be made for the transformer and switchgear equipment to work indoors.

For example, the heavy transformer couldn’t be placed on the raised floor designed for the data hall and electrical room space and wouldn’t be able to be removed from the building at the end of its useful life, as the 2500 kVA transformers each weigh approximately 16,000 lbs.

Instead, the facility was designed with the intent of moving in the transformer prior to the raised floor construction. Coordinating with the architect, saw cuts were designed into the pre-cast panels on the side of the building to make it easier for the contractor to remove/replace the exterior wall to get the transformer out for future installations or replacement.

Additionally, because the liquid-filled transformers specified are typically used outdoors, special design considerations were needed for the electrical room to contain the fluid in the event of a leak. A 4-in. metal dam was constructed along the perimeter of the room to contain the liquid, while perforated raised-floor tiles were installed around the transformer to facilitate the flow of liquid to under the floor.


Challenge No. 2: Uniform design


The owner wanted a repeatable, scalable design for each of the eight data halls to both create uniformity across the facility and provide the ability to build out data halls as needed over time. However, due to existing building conditions, including the different quantity and compact nature of the structural columns on the building’s first and second floors, an offsite modular construction design was eliminated.

Instead, the solution was to bring each component of the mechanical and electrical systems into the facility individually and build out the data halls one at a time as identically as possible.


Challenge No. 3: Medium-voltage equipment


Because the switchgear and transformers were located inside the building, medium-voltage (MV) feeders were routed throughout. The MV system itself was daisy-chained so it had to be installed and commissioned in its entirety when the first of the eight data halls were installed.

The active MV system presents a potential risk to workers during construction. Therefore, the MV feeders and conduit were routed through the ceiling of the first floor for safety, stubbing back up through the second floor slab and directly into the equipment. The feeders for the first floor equipment were routed similarly under the first floor slab. Because the eight data halls will be built out over time, this technique permits construction on the floor without subjecting workers to the active feeders.


Challenge No. 4: Switchgear and metering equipment


With very limited space for outdoor equipment, there wasn’t enough room for the utility’s 34.5 kV ground-level switchgear and metering. In addition, this equipment has not been fully vetted for the application and was seen as a risk by the owner. The only option was for the utility’s switchgear and metering to be pole mounted. This meant that the site’s 20 poles had to be spaced 20 ft from each other, taking up 400 ft of linear space on a site with little outdoor area.

The Reliability


Utility Service:

2N, or two separate utility sources/feeders, one general source and the second as backup. The switchgear is daisy-chained together, creating a connection from one switchgear to another down the line so that the power can feed into one switchgear, back out and into the other, rather than having multiple connections to the site.


Backup generators:

N+1 redundant swing generator. While each of the eight data halls has its own backup generator, another redundant swing generator for every two to three halls was designed as well, providing additional backup (a total of four swing generators in all). This provides an extra level of redundancy without the cost of providing an additional backup for each generator.


UPS system and distribution (2N):

Two sides to the electrical system were designed, where each side is a mirror of the other. The benefit of the 2N system topology allows for maintenance or a fault to occur on one of the sides, while still maintaining a completely active data center.



About Strategic Media Asia Ltd


Strategic Media Asia Ltd (SMA) is one of the Approved CPD Course Providers of the Chartered Institution of Building Services Engineers (CIBSE). SMA exists to provide an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on data center design, critical infrastructure system, electrical and mechanical facilities, etc.

SMA connects IT, Facilities and Design. For details, please visit our website at www.stmedia-asia.com/trainings.html.

Data Center Design Consideration: Redundancy

So far we have discussed about the Cooling and Space Planning issues for data center design. We all note that data centers are very special purpose-built facilities providing critical and uninterrupted services. In this section we are going to explore one of the key considerations - Redundancy.

Redundancy entails providing system beyond the minimum capacity to ensure these systems continue to operate even if part of the system fails. Under the TIA-942 Standards, data centers are classified into different tiers based on their availability and redundant designs. What exactly are these designs?


For more information of Tier Levels: N, N+1, 2N, 2(N+1), please visit our previous articles:
http://green-data.blogspot.com/2014/07/data-center-tier-levels-and-uptime.html
http://green-data.blogspot.com/2014/09/more-about-data-center-tier-levels.html


N Design

An N design means the number of components and paths is exactly what is required to meet the data center requirements. There is neither spare capacity nor any standby unit. Basically, there is no redundancy and the system will totally fail when a component or path fails.

N+1 Design

An N+1 design requires the number of components installed to exceed the requirements by one. In this case, when one of the components fails, the standby unit will take over and the system would continue to operate.

2N Design

As the name mentions, a 2N design has 2 independent working systems supporting the data center. In the event a primary system fails, a secondary system would take over and continue the uninterrupted operations.

2(N+1) Design

A 2(N+1) design is an extension of the 2N design. Both the primary and secondary systems are equipped with a single group of (N+1) facilities, e.g., each system has an extra component. This design is more resilient than a 2N design and would be able to withstand a concurrent path and component failure.


It is important to understand that in 2N or 2(N+1) systems, the secondary system should be located away from the primary system which minimizes the primary and secondary system from being damaged by any incidents, such as fire, floods, etc.

The following examples illustrate the design of a UPS (Uninterruptible Power Supply) system supplying 200kVA of power to a data center:

Figure 1: Various redundant design for a UPS system providing 200kVA of power

In an N Design, one UPS of 200kVA is installed. This design would meet the 200kVA requirements of the data center. Normal operation is disrupted when the UPS fail.

An additional UPS is installed in an N+1 Design. This brings the number of UPS system to 2 which allows for normal operation if one UPS fails. E.g., the remaining UPS would still able to support the minimum 200kVA power. However, the system can be still failure if the path (feeder cable) linking the UPS to the equipment is damaged.

A 2N Design offers protection for both path and component failures. This requires 2 UPS systems (Primary and Secondary) each with 1 unit of 200kVA UPS. Should a UPS fails to start or a cable feeder is damaged, the Secondary System would take over and continue to supply the required load.

The 2(N+1) Design is the most resilient of the 4 designs discussed. 2 systems with 2 units of 200kVA UPS each are installed. This design would continue to provide the necessary 200kVA power even if there is a simultaneous component and path failure. It should be noted, however, no design is 100% fail-proof and this design would still fail in the event of multiple failures.

The pictures below show the resiliency of various systems under different failure conditions:

Figure 2: Different redundant design under different failure conditions

The Blogger

Strategic Media Asia (SMA) is one of the 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.

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.

Electrical Design for Mission Critical Supply Course

Within the built environment, mission critical facilities have particular power requirements that significantly impact how they are designed and operated.

We are pleased to introduce a new 2-day Program in Electrical Design for Mission Critical Supply. The course content is designed for data center operators, electrical & mechanical engineers, building services managers and infrastructure managers to enrich the relevant knowledge in power system design for mission critical facilities such as data center and other infrastructure.

The course details about the power system design and the components that support typical data centers or critical facilities. It prepares individual to fully understand data centers’ electrical design & build by exploring the international Standards and sharing the speaker’s experience.

You will understand the mission critical supply system, from power components to distributions and efficiency; from power requirements to designed, testing, commissioning and maintenance.


- Concept on primary supply and secondary supply
- Power flow in mission critical supply system
- Features of major equipment for critical supply

(1) Uninterrupted power supply and power storage
(2) Backup generator
(3) Automatic transfer switch
(4) Static transfer switch
(5) Isolation transformer

- Efficiency assessment
- Power quality review
- Configuration diagram of critical supply (N+1 / 2N) design & analysis
- Review of cable sizing to incorporate harmonics content
- Earthing system design
- Testing and commissioning requirements
- Brief of Systems Merging Appraisal Test (SMAT)


For details, please visit the course content at http://www.stmedia-asia.com/newsletter_6.html


The Organizer

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.

Data Center Design: Battery-based / Static UPS or Rotary UPS?

UPSs vary greatly in physical size, weight, form factor (e.g., standalone vs. rack-based), capacity, supported input power source (e.g., single phase vs. 3-phase), technological design, and cost.

When considering the procurement of a UPS for a data center or other mission critical facility, there are a number of design and acquisition decisions to make such as:

1. The size of the load to be protected
2. The battery runtime required
3. The proper input and output voltages
4. The right type of system (i.e. on-line, line-interactive, etc.)
5. Pricing and performance seen within manufacturer product portfolios
6. The advances in technologies
7. The ideal level of redundancy (i.e., N, N+1, 2N, 2N+1, etc.)
8. The required output distribution

This time our focus will be limited to comparing 3-phase battery-based UPS and rotary UPSs that support data centers. Some of the common 3-phase UPS architectures are listed below:


- Double Conversion On-Line UPS
- Delta Conversion On-Line UPS
- Engine-coupled Rotary UPS
- Flywheel UPS


Other Single phase UPS systems (will be discussed later):

• Standby UPS (single-phase load ranges from 100 to 1,500 VA)
• Line Interactive UPS (single-phase load ranges from 0.5 to 10 kVA)
• Standby Ferro UPS (single-phase load ranges from 3 to 15 kVA)

Double Conversion On-Line UPS

This design is by far the most common type for loads above 10 kVA. A double conversion UPS is considered ‘on-line’ because its nearly ideal output waveform is derived completely from battery power through its inverter. As such, this isolates the output from the input. The input primarily serves to continually charge the battery.

Therefore, during an AC power failure, on-line operation results in no transfer time. Since 100% of the load power is converted twice, once from AC to DC (to charge the battery) and a second time from DC to AC (for the output), a double conversion UPS is inherently less efficient than offline UPS types.

These UPSs are available in a broad range of sizes for three-phase loads from 10 to 1,000 kVA. Furthermore, these UPSs can be arranged in a vast array of configurations to achieve high availability for very large three-phase data center loads.

Delta Conversion On-Line UPS

That design is a more recent topology that was originally patented and utilized exclusively by APC for its Silcon-series 3-phase UPS line.

The advantage of this topology is its energy efficiency. It achieves high efficiency by not processing 100% of the power, 100% of the time, as is the case with a double conversion UPS.

Rather, it processes only the portion of the power that is outside of the ‘window’ of an acceptable power waveform, while at the same time having an output that is on-line with load such that there is only a load step change from steady-state to full battery-load operation. As such, this technology is best suited for the highest power applications and well above 1,000 kW.

Engine-coupled Rotary UPS

A rotary UPS is one that unlike the prior approaches does not rely on electronics to pass through or recreate an output AC waveform. Rather, a rotary UPS relies on a mechanical motor and generator to create a pure sine wave output without the need for filter capacitors. Additionally, the resulting low input impedance allows the ability to handle any type of load no matter how ‘dirty’ it may be.

Also, this approach yields an ability to handle high fault currents and provide isolation from high harmonic load input currents. Finally, a rotary UPS can be configured to use direct diesel bypass. By comparison, a static (or battery-based) UPS, can only source its load from a generator in a ‘break before make’ fashion. Due to the nature of its ability to handle ‘difficult’ loads, rotary UPSs are large in size and expensive. As such, they are reserved for large loads in excess of 1,000 kW.

The advantages of Rotary UPS:

1. Most energy efficient UPS/CPS system
2. Use of stored kinetic energy
3. No batteries required, that means no chemical waste!
4. Save energy for battery room's ventilation and cooling 
5. Lowest Total Cost of Ownership (TCO)
6. Highest power factor
7. No conditioned battery room required, that means saving space
8. Long life time
9. Efficiency about 96%

Flywheel UPS

Flywheel UPS system is similar to the settings of battery-based UPS system. The rotary UPS is called “rotary” because rotating components (such as a motor-generator) within the UPS are used to transfer power to the load. The true definition of a rotary UPS is any UPS whose output sine wave is the result of rotating generation. Therefore, the UPS in Figure below, although it utilizes a flywheel as a rotating temporary energy storage source in case the utility fails, is not, by definition, a rotary UPS.

About The Blogger


Strategic Media Asia (SMA, www.stmedia-asia.com) is a leading technical training and event organizer for corporations specialized in data center design & build, E&M facilities, telecom, ICT, finance and colocation. Currently, SMA delivers a series of data center trainings and qualification programs in Hong Kong, Taiwan and Macau.

All these events / training seminars are designed to support the leadership needs of senior executives (Chief Information Officers, IT Directors / Managers, Facilities Managers, company decision makers, etc.) and to provide useful and applicable knowledge.

For detail, please visit our data center courses & training seminars at http://www.stmedia-asia.com/trainings.html.