4 FM quick reads on critical facilities
1. How To Limit Human Error In Critical Facilities
Over the last 15 years, most building operators have come to recognize people account for the majority of interruptions to critical operations. Human error is identified as the root cause in 60 percent to 80 percent of data center downtime events, year after year.
Those who maintain the critical facility's infrastructure systems require written procedures to consistently carry out riskier activities such as system transfers, when system redundancy is reduced as equipment is brought off-line for maintenance or repair. Just as important are procedures for resolving emergency scenarios. A critical facility may require 150 to 200 documents to cover both of these categories, due to the number of infrastructure systems involved. This number seems high when compared to a non-critical facility's needs. However, by comparison to another critical endeavor, it is roughly one-fifth the number of procedures required for operating a nuclear submarine.
In all cases, procedures need to be site-specific, as each facility's configuration is unique. One individual on the facilities staff must be assigned the role of procedures owner and be provided dedicated time each month to make continual progress with the program. Typically, the procedures owner is provided a contracted resource to get the program started.
Written processes are much more important when addressing areas where personnel from multiple departments have access. In the case of a data center facility, the computer room is most critical. Tasks performed there present the greatest risk of error, because multiple departments are involved and a higher frequency of human activity occurs within the room.
To reduce the high potential for error when multiple groups work together in one space, it is necessary to develop written mutual expectations between the departments involved. Some organizations refer to these as internal service level agreements. The documents can be as simple as one page, but must be endorsed by each department head and be consistently enforced.
2. Complexity Complicates Data Center Maintenance
The issue of complexity and computers resides within much of today's computer equipment. Just open the panels and cabinets of uninterruptible power supply (UPS) units and paralleling control cabinets, chiller control panels, paralleling switchgear, etc., and look inside. To most operating staff, this equipment has essentially become black boxes as well. So as the infrastructure has outpaced the staff's ability to troubleshoot and repair, the reliance on good maintenance practices becomes even more crucial.
Computers, programmable logic controllers, device-specific controllers, etc., are essentially "black boxes," which can complicate data center operations and maintenance. They typically don't give advance notice of pending failure, and when they do fail, the operating staff cannot make repairs or replacements. They have to call for vendor support and take manual control of the infrastructure involved.
The basic purpose of maintenance is to increase the availability of the equipment (and systems) being maintained. At the bottom of the pile is "corrective maintenance," or simply put, "fix it when it breaks." It takes the least effort from a management perspective, but results in the lowest availability and in most cases ends up costing the most in both total cost of ownership (TCO) and impact to operations.
The next rung up is preventive maintenance where you (hopefully) follow the manufacturer's recommendations to inspect and care for the equipment to extend its life and optimize its performance. In this case, you live with some planned unavailability (shutdowns) to afford the opportunity to care for the equipment (check belts, change filters, torque connections, etc.). The result is increased lifespan, more reliable performance, and lower failure rates.
The best practice is to supplement a preventive maintenance program with predictive maintenance using on-line condition-monitoring technologies. The most common and valuable on-line condition-monitoring technologies are thermography (infrared scanning) and vibration analysis. These monitoring techniques not only provide incredible insight regarding the health of the equipment, but actually require the equipment to be in operation, so the need for outages is reduced. By trending the results over time, a facility manager can see the health of the equipment start the inevitable decline towards predefined thresholds and "predict" when the equipment condition or performance will be adversely affected.
3. Determining Optimal Start Time Delays For Generators
The standby-generator start-time delay programming adjustment is driven by a number of factors.
Opinions range from 0.5 seconds to 30 seconds. One concern is that the majority of utility power bumps last less than 3 seconds. Therefore you can have quite a few unnecessary engine starts with start programming set for less than 3 seconds.
The short power bumps typically result from utility re-closers that automatically open and close quickly in an attempt to "shake loose" a problem on the lines, such as tree branches, animals, etc. Re-closers are often programmed by the utility to open and re-close quickly a couple times, resulting in power bumps of 1 second or less, then to remain open up to about 3 seconds on the third and typically final attempt. The fourth time a re-closer opens it typically stays open for many minutes or longer (awaiting manual intervention).
Another concern is that many times the utility fails, then returns, and almost immediately fails again. A generator start timer (typically located in the ATS or generator switchgear) will typically reset when power returns. For UPS backup energy storage, the recharge time is typically 10 times longer than the discharge time, so rapid short utility bumps can cumulatively draw down short-term storage (a very real concern for flywheel UPS systems). Multiple 3 to 10 second utility power failures within a short duration can leave a UPS flywheel too depleted to provide ride-through time.
Most engineers recommend programming generator start time delay settings in the 3 to 5 second range. If utility power is down for more than several seconds it will probably be down for several minutes or hours, so you might as well start your engines. It's best not to challenge UPS batteries any longer than necessary and risk the chance of a UPS failure. The longer a data center runs with no cooling while waiting for generator power, the greater the risk of the data center overheating. However, starting the generator for every light flicker takes its toll on equipment, with impacts on reliability, maintenance, and environmental emissions.
4. How To Avoid A "Frankenstein" UPS
To reduce the risk of getting a "Frankenstein" system of mismatched components in large UPS systems for data centers, it's important for facility managers to understand the importance of selecting a vendor with a substantial and experienced U.S. sales and service organization.
These concerns with buying complex systems from marginal players in the marketplace are well-understood among industry veterans. These concerns with UPS systems are not much different than with other complex data center support equipment technologies such as redundant standby generator systems and HVAC systems, especially central plants or HVAC systems with economizing features.
One additional key factor is not always well-understood. When an order is placed with a vendor for an integrated system of components, it is up to the vendor to pull together all the correct and compatible components and see that they arrive at the jobsite, at the same time, or are otherwise sequenced as required by the construction team. A large "single module" UPS system can require the main UPS box, boxes full of batteries, sometimes a separate battery disconnect box and often a separate maintenance bypass box, sometimes all shipping from different factories and often from different sub-vendors.
Without a strong technical sales application team, the system may not get properly represented and applied with appropriate accessories or it may not get delivered correctly in accordance with customer needs. Without a strong regional service organization, routine preventive maintenance and minor issues can lead to big problems, such as excessive planned or unplanned downtime or excessive repair time.
Imported UPS units are often matched with domestically designed and assembled battery and bypass packages. Sourcing these components is often left to the domestic sales organization, which is usually different in each marketplace. Often, a buyer thinks (or hopes) all of this equipment will be integrated together or even tested as a complete system at the "main factory or assembly plant." This is rarely the case, as it would add significant cost. Getting these different components to show up correctly at the jobsite is where the marginal players often fall down on the job.
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