,i>Providing protection for critical loads without also providing UPS protection simply transfers the risk form one component of a system to another.

You may expect an average corporate manager to be enthusiastic about installing an uninterruptible power supply (UPS) system for his or her critical loads. This is especially true if the electrical system powers extensive computer-based operations. What are the consequences when one of the nation's leading OEM computer manufacturers proceeds on the old cliche, "Do as I say, not as I do," and fails to install UPS equipment at its own facility?

Well, that's exactly what happened, and a computer manufacturer's repair parts distribution center turned to chaos. Although the electrical system had dual feeders, it went down. With no UPS to keep the operation going, failure in the accounting division affected the firm's bottom line. Some shipments were not recorded until the next quarter. Moreover, stock analysts were confident the company was in a decline-the value of their stock deteriorated. The firm's response to parts and service worldwide was slow, resulting in longer turnaround and dissatisfied customers. The cost was incalculable.

How can a forensic engineer be of service? As experts in disaster recovery implementation, we were called in to determine what went wrong and what was necessary to fix the situation. First, we had to convince senior corporate managers to install engine-generator sets that would run, if necessary, every fiscal quarter until the problem was resolved. We had to make sure this disaster was not repeated. Next, management had to recognize the reality of a long lead-time to resolve the problem on a permanent basis.

Using this approach, we could separate the short-term temporary procedures from the long-term permanent solution. To arrive at a solution, we established a team consisting of a consulting electrical engineer, some manufacturer's representatives, the client's EDP managers, and ourselves.

The answer to this problem was threefold, all of which had to be done concurrently. The electrical system had to be repaired, portable on-site power had to be brought in as an interim energy source, and a UPS system, backed up by an engine-generator set, had to be permanently installed.

Several electrical components also had to be replaced. When the facility was designed, the thinking was dual feeders would assure continuity of power and a UPS system was not necessary. The company had made provisions for future expansion, which was a contributing factor to the system's failure. Then, they redesigned the electrical system. Concurrently, they installed a UPS system for total on-line protection. The firm acquired a 500kVA system. An 800kW-diesel engine-generator set and appropriate switchgear were installed. Though costly, it was worth the money. That phase of the decision-making process did not require forensic expertise in the sense most people think of a forensic investigation. Forensic engineers often work best with one or more of the parties as a catalyst behind the scene.

If you provide UPS protection for a system without providing protection for the UPS, you're simply transferring risk from one component of a system to another. For example, UPS systems require proper and adequate air conditioning. These critical cooling systems, which capture warm air at the top and discharge cold air from the bottom, must meet the needs of the unique configurations of UPS equipment.

Traditional comfort cooling, in lieu of custom design process cooling, is not satisfactory. Process hot air discharge shouldn't "fight" comfort cooling discharge if the system is to function properly. A single cooling unit should not protect UPS systems. Redundancy is important. When a single air conditioning unit breaks down and other units are not available, it compromises UPS protection.

Another important consideration for your UPS system is choosing the battery bank's time capacity. Often, 15 min of battery capacity is sufficient. Sometimes a lower time rating will work when there is engine-generator backup. Whether or not there is a generator, the battery time capacity should be more than necessary for properly shutting down critical loads.

To avoid a weak link in any part of a system requiring critical power, you must: (1) make a prompt decision to install a UPS system at the outset; (2) use proper components in the system; and (3) employ redundant "backup" power arrangements. With greater redundancy, the client is assured that dependable critical power supply is always available. In determining the extent of redundancy, you should carry out an analysis on what the cost would be if there were a loss of power.

UPS units can be an excellent component for an effective disaster recovery plan.