Consider the typical “disaster” scenario. The power es out. Then what happens? At least one out of five times, what happens next is not what is supposed to happen. Back-up equipment fails approximately 20 percent of the time, primarily because of “infantile mortality,” or immediate breakdown under the stresses of first-time use. There is no more compelling argument for adequately testing the back-up equipment under real-life conditions when it is initially installed, although integrated system testing is overlooked in about 80 percent of critical facilities.
Granted, full system testing at installation is time- and labor- intensive, but it represents a fractional incremental expense to prevent the enormous losses of operational failure later on. On a 5,000- to 15,000-square-foot data center, testing can take several days and add about 10 percent to the total cost of the electrical system.
When you consider the common sense difference between conventional equipment testing and integrated testing under actual loads, it’s easy to see why back-up systems fail so often.
In the conventional approach to equipment testing, an engineer specifies a piece of equipment and calls for a factory witness test to verify its operability. An owner’s representative or engineer goes to the factory where the equipment is run through gentle paces (no one wants it to break). When a contractor installs the equipment, a factory rep comes to the site and does a start-up test. The equipment works; end of testing.
At a high-reliability site, testing each component separately simply isn’t enough. Under real-life conditions, no piece of equipment works in isolation, and never under a fixed, low electrical load.
Integrated system testing simulates the loads that occur in real life: as a total online system; downstream of the back-up equipment; stepped in graduated capacities up to full load and even overload; and at transient, or variable levels. If the equipment breaks, the manufacturer repairs or replaces it.
Finally, integrated testing isn’t complete until thorough commissioning is done, another common casualty of short-sighted budget-cutting. Commissioning serves as a certification of sorts, providing full documentation that all equipment has been installed and tested as it was designed. Owners often leave this up to the contractor to piece together in the haste to save days and dollars at the end of a job.
Elements of Integrated Testing
· Total system testing vs. components.
· Loads placed downstream of back-up equipment.
· Step loads (25 percent, 50 percent, 75 percent, Full, and Overload).
· Transient loads.
Misconceptions about reliability have left many companies overspent yet still underprepared for real-life contingencies. Common sense guidance can help them correct capital cost imbalances, equalize system infrastructure, and attain a reliability level appropriate to their industry. Facility managers who are versed in the components of true reliability can offer much-needed insight and value to their tenants and users.
Ann Banning-Wright is managing director of Syska Hennessy Group’s OnlinEnvironments (www.onlinenvironments.com), a leader in consulting, design, and construction of critical facilities. Based in both Los Angeles and New York City with offices across the United States, OnlinEnvironments is part of the Syska Hennessy Group, a preeminent consulting, engineering, technology, and construction firm.