When the Power Must Stay On
The reliability of the nation’s electrical grid is decreasing, and for more reliable power demand is growing. As a result of these trends, establishing and protecting critical power systems in institutional and commercial facilities is essential. Simply knowing that the experts are using “chaos theory” to analyze power systems is enough to raise eyebrows. Large-scale power problems seem inevitable.
Power problems range from traditional outages to operational issues, such as dirty power or surges. Dirty power contains noise or harmonics that prevent proper operation of equipment. Surges typically damage equipment.
Power problems are expensive and can be devastating to an organization’s business. For health care facilities, a power problem can mean the difference between life and death. In fact, power problems in data facilities can cost millions of dollars per hour.
To guard against power problems, engineering and maintenance managers can develop a strategy to protect operations by establishing critical-power supplies. Managers can accomplish this task by assessing the impact of outages versus the cost of back-up equipment and establishing predictive maintenance (PdM) procedures. By taking a reliability-centered approach, managers proactively protect against power problems.
Assessing Power Needs
Following 9/11 and the Northeast United States blackout, organizations have made a more concerted efforts to differentiate between critical power and traditional grid power. As a result, organizations are increasingly encouraged to look to their own resources for establishing critical power systems, rather than relying on the grid.
Assessing critical power needs for a facility is the first step to developing a strategic power plan.
Critical power systems consist of redundant utility feeds, emergency generators and uninterruptible power supplies (UPS). The Critical Power Coalition defines critical power as the “highest reliability and security for critical customers, at least cost, consistent with high availability/quality/security (less than 10 percent of national electric demand).”
Managers can assess their facilities’ critical power needs by taking the following steps:
- Ask, “What are the reliability drivers for my facility?” For health care facilities, operating rooms, intensive care and critical care units are obvious choices for critical power. For commercial facilities, data centers benefit most from critical power, although customer interfaces are another common choice. Often, reliability drivers extend far beyond the first point of focus. It is not just computers that need critical power. The cooling system for the room that houses the computer also qualifies, as does the computer that controls the cooling system.
- Compare the impact of power problems against the cost of back-up equipment. It can be difficult to put a price on electrical outages. The Electric Power Research Institute’s EPRI Journal estimates that U.S. economic losses due to power problems reach $100 billion per year. One way to gauge economic impact is to assess the cost of information technology systems and other equipment that might incur damage during power outages. Of course, the economic impacts of outages can be direct and indirect, including loss of production, loss of clientele, cost of recovery, and loss of earnings.
After assessing the impact of outages, managers should compare it to the cost of reliability-enhancing equipment, such as emergency generators and UPS. Most managers find that the impacts of outages quickly outweigh the cost of such systems. But the cost of critical power systems must include the cost to operate and maintain the system.
To protect critical power systems, managers can implement PdM measures, such as system monitoring. Clearly, poorly maintained equipment is more likely to fail than equipment that is properly maintained.
System monitoring helps to ensure power is there when facility systems and operations need it. Technicians can use power monitors to determine if a system is overloaded or suffering from noise, harmonics or surges. They can record data and use trending to anticipate problem areas. Newer technologies are available that use electronic signatures to track and locate potential motor failures.
Many manufacturers provide maintenance manuals outlining maintenance requirements that are too frequently ignored. For example, technicians should exercise circuit breakers yearly to keep their contacts clean and to verify operation of moving parts.
Contacts in starters can wear out. If managers rely on alarm lights, is there a push to test them, or does the software feature alarm simulations? If a facility relies on dry type transformers, do technicians use air pressure to blow out accumulated dust?
Managers should schedule regular system inspections to look for potential problems. Rigorous yearly inspections, including infrared photography to detect hot spots, can help technicians identify potential weak areas and avert disasters. Most electrical components can benefit from an infrared survey. The best candidates are circuit breakers, cable terminators, motors and moving points of contact.
Managers also should make sure their facilities’ backup systems are well documented, including up-to-date drawings.
Coping with Extended Outages
Managers can ensure critical power systems will operate as intended when needed by considering these steps:
- Test generators frequently. Technicians should test diesel generators annually to prevent build-up of carbon in cylinders, and they should cycle diesel fuel to prevent it from becoming stale. Technicians should test generators at least monthly under conditions that cause them the greatest duress. If an extended outage occurs, at what frequency must the fuel tank be refilled to ensure continuity of operations? Can a supplier commit to regular deliveries?
- Protect the investment. Many engineers rely on UPS to ensure the availability of critical power, but UPS too often are a source of failure. They have sensitive electronic equipment and require regular maintenance. Most new UPS have static bypass switches to take the UPS off line if it fails, but replacing a UPS requires a separate manual bypass switch. There are two types of lead acid UPS batteries: wet cells and valve regulated. Wet-cell batteries require frequent monitoring of the electrolyte level. Valve-regulated cells are more prone to catastrophic failure. Heat adversely affects both types. Technicians must keep batteries in a cool environment to ensure they operate when needed.
- Develop outage operating scenarios. In many institutional and commercial facilities, it's not uncommon for electrical loads to drop during power outages, causing people to stop working. Organizations can save money if critical power systems address working loads under the conditions in which they will be forced to operate in an outage.
The Role of Manufacturers
Manufacturers play an important role in protecting critical power systems. Manufacturers of equipment for these applications know their reputation rides on meeting customer expectations for critical power. But success is a two-way street: engineering and maintenance departments must correctly apply and maintain the equipment, and they must clearly document activities and explain supporting information.
Many manufacturers now go the extra mile by developing systems that automatically download equipment status to internet addresses, or that send alerts and maintenance information back to the system monitor.
A combination of PdM, effective documentation, reliability-enhancing equipment, and collaboration with manufacturers will go a long way toward protecting critical power systems.
Managers seeking more information on critical-power systems, as well as the the required testing and monitoring to ensure their effective operation, can check out the resources and activities of these organizations:
— Dan Hounsell
Jim Degnan, P.E. is principal of a design studio specializing in military, industrial and jail projects at Sparling, an electrical engineering and technology consulting firm with offices in Seattle and Portland.