You’re reading an outdated article. Please go to the recent issues to find up-to-date content.
Politics, economics and cautious restraint are needed:
Someone from Europe asked, “What have you learned since the blackout of 2003?” I shared my observations of what I thought has happened (or not happened) since. Such problems aren’t confined to our grid, though you don’t hear about the blackouts in Europe with the same tenacity of media coverage of those in the United States. They also don’t seem to be followed by the same dire predictions of those out to capitalize on these events for their own political and economic gains. But the European electrical system is completely not immune from such.
In the same year of the infamous August 14th blackout in the Midwest and Northeastern United States and Ontario, Canada, there were blackouts in Italy, the United Kingdom, Spain, Denmark, Sweden and other countries. In 2004, the Parliamentary Assembly of the Council of Europe passed Resolution 1413, “Avoiding electricity blackouts in Europe,” which addressed “the weak links in Europe’s electricity supply networks, insufficient co-ordination between national or regional electricity markets and, occasionally, insufficient production capacity.” Sound familiar?
Similar events have happened in the United States, with committees appointed, investigation undertaken, and reports commissioned, which are then followed by more studies and more reports with more recommendations. But has this made the quality of the interconnected electric supply more reliable in North America? This question could draw affirmative and negative answers, supported by equal amounts of vigor and data, depending on the sponsor.
Fortunately, such large-scale events are not very frequent. I think most people would agree that there is still the potential for them. I have witnessed increased tree trimming by our local utility (identified in the FERC report as being a contributing factor to the blackout). I also read a contrasting article in the local paper where the residents are objecting to the local utility running a 230 kV line through an underground pipe that was installed a number of years ago for such a purpose, which would also address an issue from the report concerning inadequate transmission reserve capacity during peak demand periods.
What is really happening is most likely a mix of politics, economics and historical “cautious restraint” that has governed changes in the electric utility industry for years. Perhaps a better question would be the personal one. To paraphrase President Kennedy, “Ask not what your utility can do for you, but what you can do for your customer?” To just install a very large generator with a break-before-make transfer switch might not be the best economical solution, nor actually make the system more reliable. Though the line in the utility perspective between reliability and power quality tends to centered around events lasting longer or shorter than one minute, respectively, it is really about the reliability of the customer’s processes.
The steps are neither very complicated, nor necessarily expensive to implement, and the payback is often simple to compute. First, determine what equipment is critical to keep running for what periods of time. It might only take 30 seconds for an orderly shutdown with proper notification. Next, conduct a monitoring program of at least one week to determine what are typical types of PQ disturbances that occur. Matching these up with the susceptibility of the critical loads determines what type and size of mitigation equipment is most likely to improve uptime/minimize downtime.
The next step is to either rewire or relocate the equipment to the minimal number of circuits that need to be powered and/or protected. It is important to also include protection for any communication systems, such as phone lines, cable, etc. The proper size uninterruptible power supply (UPS) that is able to generate load-rating voltage fast enough should be coupled to a transfer switch that is also fast enough to keep the process running in the event of a power interruption.
A step that can be overlooked (or avoided) by some is the fully load test. It is much better to know from the beginning under controlled circumstances than during a crisis. It isn’t enough to say that it looked like things kept running fine, so it will continue monitoring the electrical system at the critical loads. The transfer time might have been marginal, or the recovery from the event may have produce voltage swells that may be damaging to the critical loads. This type of information is only possible to determine if the voltage and current on all phases (including neutral where applicable) are monitored throughout the tests. It also provides a baseline to compare against in the future.
Which leads to ongoing preventative maintenance. To just install a UPS and leave it be is a waste of money. Having an effective maintenance program that covers all aspects of the system is as critical as the proper installation. Consult the manufacturer’s manuals and publications such as the NFPA 70B Recommended Practice for Electrical Equipment Maintenance for information on this. Such EPM programs can be both an ongoing source of income for an electrical contracting company as well as for preventing loss of income for the customer. EC
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680.