Commissioning: Electrical System for Mission Critical Supply (3)

Refer to Previous post: Commissioning: Electrical System for Mission Critical Supply (2)


Generator Paralleling Switchgear

This is a crucial component to a critical facility in situations where the generator supported load exceeds the capacity of one generator.

Generator paralleling switchgear systems should be tested at the rated power factor of the generator paralleling switchgear system—typically 0.8. This is important to show that each generator properly shares the kW and kVAR loads. Just because paralleled generators evenly share kW while serving a resistive load does not always mean that they will evenly share kVAR when serving a reactive load.

A major challenge with testing generator paralleling switchgear systems is that they are often rated for very heavy loads due to the number of generators that can be connected to them. In some cases, it may not be practical and may also be very expensive to load generator paralleling switchgear systems to rated capacity.

It is recommended that enough load be provided so that it exceeds the capacity of one generator. Ideally, the load banks provided will be sized to the expected operational capacity of the generator paralleling switchgear, but not necessarily to its full design capacity.

Generator paralleling switchgear systems rely heavily on programming within the programmable logic controller (PLC) for operation. Knowledge of how this program operates is often limited to a handful of experts. Changes to PLC programming must be documented in a PLC programming change log. The log should include the date of the change, the reason for the change, a description of the change, and the new version number of the program that includes the change. Older versions of the program should be saved in the event that updates create additional problems and reverting back to an earlier version of the program is required.


Main Electrical Switchgear

It is also an important component to a critical facility because it distributes power to all of the downstream electrical distribution equipment.

Circuit breaker settings must be inputted, coordinated, tested, and verified throughout all main electrical distribution equipment. If there is a fault in the system, it is imperative that selective coordination is implemented so that the fault is isolated as far downstream as possible.

Main circuit breakers must be properly set up to ensure that they will stay closed during fault conditions and wait for downstream equipment to clear the fault. This will be ensured by implementing proper National Electrical Testing Association-recommended circuit breaker testing including instantaneous pickup, short time pickup, short time delay, long time pickup, long time delay, ground fault pickup, ground fault time delay, contact resistance tests, and insulation resistance tests.

While main electrical switchgear is an integral part of the electrical distribution system, the system’s current carrying capacity may increase the arc flash hazard. To avoid injury, main electrical switchgear should be disconnected before it is opened or worked on.

Because the owner will often not own a means of disconnect ahead of this equipment, it usually requires involvement from the utility provider, which can be problematic and difficult to schedule.


Static Transfer Switch (STS)

An STS is an important and useful component for a critical facility because it provides the ability to seamlessly transfer load during both failure and maintenance situations.

STSs behave similarly to ATSs, but because they are designed to transfer within a few msec, there are several settings that must be coordinated. STSs are commonly fed from UPS systems. These UPS systems are present to prevent interruptions to the downstream STSs. During a planned maintenance event or during a utility power failure, the UPSs are designed to perform transfers to bypass or battery within a certain time frame.

Because the STSs are set up to transfer on a loss of the primary source for a certain duration, the time frame must be longer than the allowable interruption seen from the UPS. If not coordinated properly, a routine transfer to bypass at the UPS level can cause the downstream STSs to transfer to their secondary source.

On several occasions, phantom voltage and current readings have been observed at the STS screens with no connected load. Rebooting the system typically corrects this problem. While the manufacturers generally indicate that there are no operational risks, this anomaly is puzzling.


Electrical Power Monitoring System (EPMS)

The EPMS allows all of the electrical systems within the critical facility to be monitored from a single location, giving the operator visibility to ensure that all systems are not generating any alarms and are operating properly and efficiently.

When confirming that the EPMS is monitoring systems correctly, multiple states must be checked for each point. Points must be modified in the field and checked to ensure that the same values or statuses observed in the field are properly reported back to the EPMS.

One difficulty encountered in this area has to do with discrepancies with points. Design engineers typically specify points to be monitored by the EPMS, but they often approve equipment submittals that are unable to provide these points. To avoid this problem, it is best to meet with the design engineer and the equipment manufacturers prior to the acceptance of the submittals to ensure that the points that are important to the design engineer can be provided by the equipment.


Conclusion

The equipment in the electrical distribution system of mission critical facilities must operate dependably. After commissioning challenges have been resolved and best practices have been employed, these systems will meet the original design intent and owner’s requirements, ensuring the owner that the facility embodies reliability, redundancy, and resiliency.

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 SMA's Technical Training Seminars & Data Center Qualification Programs.

Commissioning: Electrical System for Mission Critical Supply (2)

Refer to Previous post: Commissioning: Electrical System for Mission Critical Supply (1)


Automatic Transfer Switch (ATS)

The ATS is an important component of the critical facility because it is used commonly in critical facility designs to transfer power from a primary source to a secondary source after the loss of the primary source.

Open transition ATSs are designed to allow for an interruption to the load using a break-before-make transfer. Because of this, loading the ATS during open transition transfers during functional performance testing is not required. Load is also not required when testing an ATS’s ability to perform closed transition transfers. During closed transition transfers, the ATS will parallel the primary and secondary sources prior to transferring.

It is important to ensure that the ATS can properly conduct closed transition transfers and will handle the transition in the same manner, regardless of whether it is carrying load or not. A power quality meter must be connected to the output of the ATS to confirm that the transfer is completed within the specified time for closed transition applications. It should be noted that load is required for all ATSs when conducting infrared scanning.

It is recommended that all components of the ATS are infrared scanned under full load on all primary, secondary, and bypassed power paths after final installation is complete. Load is also required for closed transition applications when the secondary source of the ATS is a generator. This testing is usually conducted as an integrated system test to prove that the generator and ATS work properly together under full load. The integrated system testing is conducted after functional performance testing for the ATS, generator, and other integral systems is completed.

In most cases, for an ATS to be functionally tested, both sources must be available because the ATS will usually inhibit any transfer if there is only one source. This problem can arise in situations where ATSs are added to existing live facilities. Because of their integral role in the power distribution system, they often can’t be tied into the electrical system without bringing down the loads that they will serve. In an effort to minimize disruption to the live facility, the ATS testing will likely occur prior to connecting it to the live facility.

However, the ATS can be connected to the secondary source if the secondary source is a generator. When the primary source serving the load is restored, there is usually limited time for testing the ATS as it will immediately be required to provide power to critical loads.


UPS

The UPS is a critical component to supporting critical loads, as it is the primary system responsible for maintaining continuity of load during a loss of utility. Courtesy: ESDThe UPS is probably the most important piece of equipment in the critical facility because of its ability to maintain power to critical loads, regardless of the operation of all of the other supporting systems.

Monitoring the inputs to the rectifier of the UPS, the static bypass within the UPS, and the UPS output bus is considered best practice during functional performance testing. After each transient, step load, or battery discharge test, the waveforms recorded by the power quality meters set up on the system should be reviewed to confirm that no events were triggered and that the output waveforms stayed within tolerance and recovered within the specified time frame.

UPS systems are often placed into service quickly after functional performance testing, so it is best to check the power quality meter results—including waveform captures—during on-site testing rather than waiting for a report from the meter technician. This way, any problem discovered during UPS testing can be quickly rectified as the manufacturer often has to consult the factory on problematic internal UPS operation.

Full load endurance tests should be conducted on UPS systems after the system has been installed on-site, even if full load testing was conducted in the factory. Many components need to be disconnected for shipping and are then reassembled on-site. Electrical equipment can also be affected by problems that develop during shipping and may not be detected without performing the endurance test on-site. Generally, an 8-hr duration for a full load test is considered adequate to confirm that the system will be capable of functioning at full rated load without problems.

In some cases, it can be difficult to monitor the logic used by the UPS to handle various operations because the actions are carried out by microprocessors installed on circuit boards. This emphasizes the importance of properly setting up power quality monitoring equipment prior to testing the UPS.

If a problem is detected during testing, the manufacturer will have a much easier time solving it if it is provided with significant data generated both by the UPS’s internal monitoring system and the external power monitoring equipment used during testing. When a failure occurs, it can be very difficult to understand what is happening inside the equipment. Captured test data almost always improves the issue resolution process.


Next Post: Commissioning: Electrical System for Mission Critical Supply (3)

Commissioning: Electrical System for Mission Critical Supply (1)

Critical Facilities Engineers should overcome the inherent challenges with functional performance testing for their electrical system.


The overall goal of commissioning must be to ensure that a facility meets the design intent and the owner’s requirements. For critical facilities, this goal is generally achieved by proving to the owner that the reliability, redundancy, and resiliency that he or she paid for is indeed present and operational in the finished facility.

Because there are so many failure scenarios and variables, it is rarely possible or cost efficient to reasonably test each one, but the commissioning authority has an obligation to provide a level of testing that will allow the owner to feel confident that each system is working and capable of maintaining a proper planned operational state during common external events.

As expected, the owner will want to use the commissioning process to be certain that the installation, performance, and operation of new equipment is acceptable before it supports critical load, and he or she will strive to do this as cheaply and as quickly as possible.

In the forthcoming posts, we will explores the best practices for testing several electrical systems, as well as some of the challenges encountered. Implementing these best practices and lessons learned on future projects will improve the quality of the product provided to the owner:


(1) Generator
(2) Automatic transfer switch (ATS)
(3) UPS
(4) Generator paralleling switchgear
(5) Main electrical switchgear
(6) Static transfer switch (STS)
(7) Electrical power monitoring system (EPMS)


Generator

Including the generators in the commissioning scope for a critical facility is imperative because they are the only source of long-term standby power when the utility becomes unavailable.

When testing a generator, it is best practice to ensure that the load for step loading and endurance testing has a power factor rating that matches the nameplate power factor on the generator, as the generator will be tuned and calibrated to operate best at its rated conditions. The manufacturer also will not likely be able to provide documentation on how the generator is expected to perform if the load used for testing deviates from the name plate conditions. The tuning and calibration is especially important when attempting a 0% to 100% step load, and often the system will not respond properly within acceptable tolerance if the power factor of the load does not match the nameplate rating.

Due to new some regulations in several countries, generators are now limited regarding the amount of pollution that they can emit under all running conditions, including when responding to step loads. This has been a challenge for generator manufacturers who in the past simply allowed the system to call for more fuel, which resulted in billows of black smoke entering the environment. In an effort to minimize pollution, manufacturers have had to finely tune the generators, resulting in the increased importance of testing the generators at rated power factor. In addition, because the generators are typically exercised under load for routine maintenance and testing, the owner often buys a permanent resisted load bank (unity power factor) sized for the rated capacity of the generator. It is important to explain to the owner that the permanent load bank that will be used for future load testing may not be appropriate to use during commissioning if it is rated at unity power factor.


Next Post: Commissioning: Electrical System for Mission Critical Supply (2)

Invitation to Data Center Technical Visit + CPD course in Critical Facilities Design

2-day CPD course in Data Center Facilities Design
and Infrastructure Engineering (20 - 21 February 2014)

(HKIE CPD Course Code: CPD0227)

The 2-day CPD 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.

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: 20 - 21 February 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

Fee: Special rate for HKIE's all membership classes

For detail 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=2936) or contact (852) 2117 3893.

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 Center in Tseung Kwan O
TELEHOUSE HONG KONG CCC

Sponsored by KDDI Hong Kong Limited (www.kddi.com.hk)

Further to the HKIE CPD Course, the half-day technical visit targets to provide an interactive environment and opportunities for members of IDC industry to exchange professional views and experience on critical infrastructure / E&M facilities:

Date: 12 February 2014 (Wednesday)
Time: 13:45 - 17:15
Meeting Point: Exit D, Kowloon Tong MTR Station (Please refer to a rundown attached)

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

Remark:

Business Card and HKID Card are required for the on-site registration. KDDI Hong Kong reserve the right to refuse any unexpected registration for the Technical Visit. In case of disputes, the ultimate decision will be reserved by KDDI Hong Kong.

TELEHOUSE HONG KONG CCC

TELEHOUSE HONG KONG CCC (Telehouse Hong Kong Cloud Computing Complex) is one of the largest (360,000 sq.ft) and most technologically advanced carrier neutral data center facilities in Hong Kong and in the Asia Pacific Region.

Operated by KDDI Corporation, TELEHOUSE HONG KONG CCC is a Tier 3+ purpose-built data center facility that is strategically located in Tseung Kwan O, Hong Kong. With virtually no risk of natural disasters in the vicinity, TELEHOUSE HONG KONG CCC is ideal for securing mission-critical business systems.

For detail, please visit http://www.stmedia-asia.com/data-center-tour.html

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 SMA's Technical Training Seminars & Data Center Qualification Programs.

Merry Christmas and Happy Year 2014

Season's Greetings - Merry Christmas and a happy, healthy and prosperous new year of 2014 from Strategic Media Asia Limited (SMA)

Data Center Cable Management (2)

Peek into the data center, and you might spot server racks sporting snarled messes of spaghetti cabling instead of neatly tied bundles. Several strategies can help to consolidate and better manage computer cabling in the data center.




Implement a converged networking architecture

With the increased density of servers, storage and networking devices, cabling needs also increase. Blade server systems converge IO and networking to connect servers; storage; networks; and keyboard, video and mouse (KVM) systems. Using converged networking adapters (CNA) or mezzanine cards in blade systems enables the same adapter to be used for both storage and general network activity. Converged adapters simplify connectivity and improve flexibility in how CNAs will be deployed going forward.

Network devices such as switches are often added to server and storage cabinets. For example, a top-of-rack, bottom-of-rack or embedded switch aggregates the network and I/O connections within a server cabinet to simplify connectivity to an end-of-row or group of switches. Low-performing servers or storage can use low-cost, low-performance network interfaces to connect to a local switch, while a high-speed uplink connects to a core switch.


Deploy cable management technologies and best practices

Do you know which cable goes where and what it connects to? Can you easily identify different types of networks by looking at the cable or identifier tags? Are power and network cables clearly identified? If not, your organization needs some form of a cable management system.

Cable management systems, including patch panels, trunk and fan-in, fan-out cabling for overhead and under-floor applications, are useful for organizing cabling. Cable management tools include diagnostics to verify signal quality and dB loss for optical cabling, cleaning and repair for connectors, as well as asset management and tracking systems.

For a relatively low-tech option, label cable endpoints to track what the cable is being used for. Solutions can be as simple as a Microsoft Excel spreadsheet or as sophisticated as a configuration management database with intelligent fiber-optic management systems. An intelligent fiber system includes mechanisms attached to the cabling to facilitate tracking and identify cabling.


Verify airflow in and around cabling

While not typically considered green IT, cabling can impact airflow and, in turn, data center cooling costs. A well-designed cable conveyance system enables easy access for maintenance while allowing cool air to efficiently circulate where needed. Improved airflow means air conditioning doesn’t have to work as hard, which reduces power consumption and energy costs.

Deploy Cat 5 for KVM needs

Simplify support for KVM devices by seeking solutions that leverage Category 5 cabling to let Ethernet wiring do double duty. If network consolidation leaves your organization with unneeded Cat 5 cabling, repurpose it to support KVM needs.


Don’t create problems by cost-cutting

In the quest to reduce costs, there can be a temptation to cut corners with lower quality cable and connectors. This can cause problems. For example, consolidating too much onto a single resource or cable can create a single point of failure. Invest in quality cabling to reduce total cost of ownership.Without cable and associated management, servers, storage and network devices aren’t able to communicate with each other, access the power they need or be monitored. Proper cable management can help maximize the return on your investment in technology.


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.

Data Center Cable Management (1)

Data centers represent some of the most demanding performance technology in the communications infrastructure market. Choosing the right cabling and cable management system is one of the most important aspects of data center design. Reliability, in combination with extreme density, should guide your choice of products. Data center longevity is also a consideration, especially when it comes time to upgrade to 40G and 100G Ethernet.

Tight Buffer Cable

Cabling infrastructure is the backbone of your data center. The rugged characteristics of tight buffer cabling reduce risk of downtime caused by cable failure. With increasing density and the subsequent increased risk of strain on your cabling system, reliability is essential when evaluating cabling needs.

Fiber is immune to electromagnetic interference and is specially designed for higher bandwidths (data rates) than other types of cables. As fiber becomes the prominent transport medium in the data center, it’s important to research and select the latest in data center products and technologies. Choose companies with experience in developing and supplying cable products perfected for the most critical communications applications.


Preterminated Fiber and Copper Cabling Systems

The sheer number of connections in the data center has increased dramatically and will continue to do so with the advent of the 40G and 100Gbit/s Ethernet standards. These new standards require increased fiber counts for a single data connection beyond the conventional duplex configuration. Look for the highest density of connectivity. Preterminated copper and fiber cables are the preferred choice for several reasons.

First, the operator is less of a factor in the termination process required for either fiber optic or copper cables since no special skill set is required for termination or testing of preterminated cables. This also eliminates the concern of alien crosstalk testing on the copper side. No external contractors are needed, saving your company both time and money.

Secondly, preterminated cables eliminate excess loops, as they are cut to specified lengths. Preterminated copper or fiber optic cables can be customized to your specific needs for easy, perfectly cabled installation, eliminating the problem of excessive slack storage.






10G Copper Cat6A PoE Ready Preterminated Cabling System

If your data center supports PoE enabled devices, such as cameras for surveillance and security or IP telephony, then copper cabling may be an appropriate choice for your facility. Choose products that allow you to build a foundation that will support both high-speed data and provide device power simultaneously. Preterminated Cat6A panels and cabling systems offer the foundation you are looking for to support current and future PoE devices.


Integrated Cable Management

Cable management is the key for accessibility and a clean visual appearance of any data center. In recent years, this has become even more pressing as the value of rack space has driven densities for both copper and fiber applications.

Combined with the high data counts for the 40G and 100GBit/s Ethernet standards, cable management has seen an unprecedented level of interest to accommodate the densities of today and anticipated densities of tomorrow. Ideally, choose products that ensure accessibility of all ports, have horizontal and vertical management mechanisms on the front of the panel, and smooth coupling mechanisms between the cassettes and the panel chassis.

Upgradability

A solid technical roadmap is key to installing infrastructure that is suitable for your current needs, as well as accommodating both anticipated and unanticipated needs for the future. Spend some time now researching the marketplace and choose products designed specifically with this in mind.

Choose fiber cassettes that are upgradable from 10G Ethernet to either 40G or 100G, and panels suitable for all technologies. Preterminated trunk cables used for 10G today can be leveraged into 40 or 100G tomorrow, simply by installing the respective new technology cassettes that suit your bandwidth needs.


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.

Certified Data Center Design Professional (CDCDP)

You are cordially invited to join the credential program organised by CNet Training, UK

CDCDP, Certified Data Center Design Professional, combines with 3-day Core Unit and 4-day Advanced Unit delivered by experienced instructors from CNet Training. It targets to electrical & mechanical engineers, facilities / data center managers, data center operators, system analyst, IT management, etc. who are responsible for critical infrastructure and facilities.


The 3-day Core Unit of CDCDP covers key theories for data center design and international standards, whereas the 4-day Advanced Unit of CDCDP combines with four modules - Data Center Efficiency, Cooling, Design Management and Power - more focused on the best way to implement the design processes.


Completion of the two units and examinations will receive a Level 5 accreditation (Certified Data Center Management Design Professional, CDCMDP) granted by (BTEC) Edexcel, a Pearson group. All units are conducted in English by instructors from CNet Training, UK.


Kindly visit the local site of CDCDP at www.stmedia-asia.com/cdcdp or download a detailed program brochure HERE. You can also visit the official site at CNet Training (www.cnet-training.com/regions/asia-pacific).






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 co-location services. Based in Hong Kong, SMA currently delivers a series of data center training courses and credential programs in South China regions.

SMA is an authorized regional agent of CNet Training in Hong Kong, Macau, Taiwan and South China.

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

Strategic Media Asia becomes a CPD Course Provider of the Hong Kong Institution of Engineers (HKIE)

We are pleased to announce that Strategic Media Asia Ltd (SMA) becomes one of the CPD Course Providers of Hong Kong Institution of Engineers (HKIE) during 20 - 21 February 2014:


Data Center Facilities Design and Infrastructure Engineering


Further to the professional members of IDC industry and the management of critical infrastructure, the course is also designed to suit CPD needs of Scheme A trainees and Corporate Members of HKIE.

SMA, a critical infrastructure training and event organizer based in Hong Kong, will continue to provide 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 more information of the training programs and industry events, please visit HERE.

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.