Mission Critical Care: Eight Design Tips to Get the Best Power System Life Expectancy
When a well-designed emergency power system is well maintained, it will remain dependable for many years. Ten touch points (see the figure) affect the life expectancy of these systems, which are the lifeblood of a commercial, industrial, or almost any facility. Design is just the first of these key touch points
The term design refers to the design of the facility, the emergency power system itself, the elements selected to be part of that system, and the programs to support and sustain this system in ready condition. The owner/user, the owner’s consultant, construction manager, contractors and vendors comprise the team responsible for design and execution; each member has unique responsibilities, skills, and experience.
1. The emergency power system must be mission–centric, but to achieve this goal, the owner, and end user must establish a mission for the facility–and define its future missions. The data center primarily manages and processes information consistent with the demands and expectations of its customers.
Moore’s Law illustrates the magnitude of this task. Wikipedia defines Moore’s Law as “the empirical observation made in 1965 that the number of transistors on an integrated circuit for minimum component cost doubles every 24 months.” Today almost everyone carries and manages more data than entire computing systems did when Gordon Moore made his famous observation. Indeed, many data centers are being built to meet the demand for data services provided to individuals. As the general population relies more on personal devices and virtual workplaces, the demand for data services will only increase. The greatest challenge for industry is to meet the exponential demand for data services while coping with the inability of manufacturers to provide required efficiencies and remaining environmentally responsible business citizens.
2. Consultants have the primary task of transforming the present and future mission of the facility and the requirements of the owner/user into the physical and electrical design while also writing equipment specifications, establishing a formal commissioning program, and developing the schedule all within the budget and time allotted. The consultant cannot accomplish these tasks alone. Each member of the design and implementation team from the owner to the vendor must contribute.
3. The equipment specified to for the emergency power system is very important; however, the selection criteria of critical equipment must go far beyond its cost. Owners and consultants should look beyond initial specifications and understand how individual manufacturers arrive at their published specifications, their development process, the design standards, and tests required by those standards. What is the manufacturer’s track record? What Quality Assurance standards and programs are in place? Where is the equipment designed and manufactured? What service support is available? Price is important, but price alone should never be the only decision criteria.
4. The engines, power transfer devices, and system controls must be maintainable. For example, power transfer switching devices should enable personnel to bypass connected loads, so that routine preventive maintenance may be carried out without impact. Switchboards must provide the ability to isolate or re-route power to allow for safe routine maintenance.
While maintenance scheduling is important, workplace safety is mandatory. Working on energized equipment creates exposure to arc flash hazards. The energy released by a fault or an electric arc is hotter than the surface of the sun (roughly 35,000 degrees F) and moves at speeds of 5000 feet per second. It is essentially a fireball, which is inescapable. Systems must therefore provide the flexibility to allow power to be safely bypassed or re-routed for maintenance and repair while continuing to provide power to essential loads. Those working in and around energized electrical systems are required by NFPA 70E to wear appropriate personal protective equipment (PPE). The class of PPE required depends on the classification of the hazard. It is ironic that the equipment designed to protect individuals from the dangers of arc flash hazards, severely restrict dexterity, sight, and agility, making anything but the most rudimentary task virtually impossible. Use of this equipment is restricted to operating system components (circuit breakers, bolted pressure switches, isolation bypass features etc.) making physical observations and taking test readings.
5. Advances in technology have produced control platforms that are much more powerful and flexible than those of a few years ago. While it is tempting to develop very complex systems and controls presumably capable of meeting every operating demand, too much complexity may actually decrease reliability. Other members of the design team and manufacturers can help assess the realities of system design and suggest alternatives to increase reliability.
6. Individual system elements must complement each other. Once assembled, the entire system must perform as one unified piece and be transparent to the data center. To achieve this goal, controls must be functionally compatible and systematically coordinated, especially when the emergency power system is being modified or expanded. In a few short years, some control devices or platforms may become obsolete, so adding incompatible devices creates great difficulty. For example, a new generator may include a voltage regulator that is not compatible with existing components or an alternator with a different winding pitch. Here again, using the group expertise of the consultant, engine generator manufacturer and control systems manufacturer makes a difference
7. The entire team must understand the realities of the project schedule. The one that never seems to change is the cutover date. Too often, delays on the front end of the acquisition, installation, and commissioning process result in extreme pressure as the cutover date nears. This pressure, in turn, may cause shortcuts to be taken, tests to be truncated, or oversights. Failure to allocate the necessary time to a methodical commissioning process reduces long-term system reliability.
One of the most common delays occurs during the proposal and submittal process. In response to an request for a proposal, vendors and suppliers provide submittal documents detailing what they will provide. The consultant and the owners have to respond to the vendor with either a release or an exception. Many manufacturers do not schedule a manufacturing slot until the submittals are released, causing delays, which at this stage of the project only serve to reduce the team’s ability to provide a fully commissioned system on schedule.
8. Sustaining dependable operation of the emergency power system requires design of support programs. Managing the intellectual property associated with the emergency power system is absolutely necessary. Operation and maintenance manuals, as-built drawings, maintenance and testing records, current one-line feeder diagrams, and programming media must be organized and maintained current. More often then not, critical information is missing, outdated, or damaged. As with IT operations, this library of information should be audited for correctness, duplicated, and archived at another secure location. Systems and products available today enable hard media to be converted, stored, and maintained in electronic form on a secure server and accessed from anywhere on the globe via the Internet.
Those responsible for operation of essential systems must be trained to understand and operate them, and this requires a dynamic training program to maintain staff expertise and train new members as they come on board. Manufacturers of the system components will be able to provide portions or complete training programs for building staff. Finally, an integrated maintenance program consisting of expert representation for all system components will help ensure longevity and reliability. Service providers should answer some questions about their ability to support acritical system and provide references.
The design of the emergency power system is anything but simple. Ultimately the design must meet the requirements of the facility’s mission while encompassing flexibility, redundancy and maintainability and balancing the demand for energy with the social responsibility of efficient design.