By Damien Polansky
Some of us live in parts of the world where accessibility to dependable power is taken for granted. But power shortages, rolling brownouts and regional blackouts continue to challenge global power systems. Aging infrastructure, increasing demand, natural disasters, adopting and connecting to new forms of renewable energy generation all contribute to these challenges.
Reliable power is in every nation's best interest, so these challenges must be addressed. Gross domestic product growth depends on it. The relation between energy and economic growth was a key topic during the recent World Economic Forum. Peter Voser, Royal Dutch Shell CEO and Energy Community Leader 2011 Peter Voser addressed the forum.
"Without heat, light and power, you cannot build or run the factories and cities that provide goods, jobs and homes, nor enjoy the amenities that make life more comfortable and enjoyable," he said. "Energy is the oxygen of the economy and the lifeblood of growth, particularly in the mass industrialization phase that emerging economic giants are facing today as their per capita gross domestic product (GDP) moves between approximately $5,000 and $15,000."
From urban areas where power helps economies thrive to remote villages dependent on a single wind turbine to light a classroom, energy derived from a multitude of resources is harnessed into power systems that must deliver according to consumer expectations. That power is available at the flip of a switch, push of a button or plug of a cord to execute needs in the home, at the workplace, on the farm, in a manufacturing plant, school or health care facility.
As old power grids are rehabilitated and new ones are built, consider the role of the power cable and why adherence to strict quality and manufacturing standards for cable construction is crucial to reliable, long-life power systems. Utilities and independent power providers (IPPs) must place more attention on whether the cables they purchase and install adhere to those standards for quality and performance. Making sure rehabilitated and new systems are built to last for decades requires quality that begins with the materials that go into cable construction and the premise that not all cables are created equal.
Quality Materials Matter
The power industry has a range of suppliers and materials to choose from when deciding cable construction, specification and installation. Cable manufacturers are looking for materials that deliver ease of processing for robust, consistent manufacturing that minimizes insulation-related stresses during fabrication. Installers look at flexibility, stress-crack resistance and shield strippability that reduces accessory-related risks for splices and terminations during installation. Utility engineers care about high electrical breakdown strength that ensures failure-free operation and lower electrical losses over the lifetime of the cable.
These performance attributes are possible only with the use of quality raw materials tested to perform according to industry specifications. Cable makers, system developers, insurance providers, utilities and IPPs alike should ask about the kind of technology, clean manufacturing and packaging techniques, testing and validation that goes into raw material production. All cables are not created equal, and strong up front consideration of the benefits that quality materials bring to power cable design and construction is essential.
To further elaborate the point, consider the growing dominance of tree-retardant cross-linked polyethylene (TR-XLPE) for underground (UG) medium-voltage (MV) power cable applications. XLPE emerged in the 1970s as the preferred insulation type for MV UG power cables because of its quality, cost competitiveness and reduced long-term operating costs. Ongoing study of XLPE in wet UG conditions led to the development of water tree-retardant XLPE, or TR-XLPE insulation, for UG power distribution cables that have become the standard bearer vs. cables made with XLPE and ethylene propylene rubber (EPR) materials. A study shows actual field aging of cables buried for 17 years (see Figure 1). From the excellent retention of dielectric strength derived from that study, along with data from accelerated wet-aging tests, it generally is accepted that cables made with TR-XLPE materials can last 40 years or more.
|Figure 1: PEM Fuel Cell|
Cable Standards Matter
Materials suppliers and cable manufacturers have been challenged for years with this mindset: Cable often is seen as a commodity, and many people assume any standard utility cable will operate just fine in any given system. This mindset sometimes allows short-term financial considerations to overrule long-term investments toward reliable, long service life solutions that can result in a lower total cost of ownership during the life of the system. Economic sustainability for power providers depends on how long systems last underground, below the sea or overhead without failures. Cables made with quality materials to exceed industry specifications ensure sustainability for end users and the entire value chain.
With this in mind, Dow Electrical & Telecommunications (Dow E&T) began its Dow Inside initiative in 2009, which brings the company's technology together with cable manufacturers to fabricate cables that exceed global industry standards. Under the program, select cable manufacturers have the opportunity to become licensees that manufacture cables with Dow materials according to high standards. In exchange, Dow E&T supports the cable manufacturers with technology, proven products, enhanced service and a creative and responsive partner.
To date, the company has signed agreements with 11 global alliance partners in North America, Europe, India and Asia. These cable manufacturers use Dow Endurance products to make MV, high-voltage (HV) and extra-high voltage (EHV) power cables.
All cables made with the company's MV products have undergone rigorous testing and meet or exceed the following standards:
• North American: ANSI/ICEA S-94-649, ANSI/ICEA S-97-682
• European: CENELEC HD620, IEC 60502, 60840, German DIN VDE 0207, 0276
• Chinese: Power Industry Specification DL/T 1070
HV and EHV cables made with the company's materials meet and exceed all globally mandated requirements including IEC 60840/62067 or other equivalent international standards.
In addition, many testing institutes and other organizations work with companies such as Dow E&T and its cable manufacturer customers to ensure raw materials and the cables produced from them meet recognized national and international standards. These testing institutes and organizations include: National Electric Energy Testing Research and Applications Center (NEETRAC) and Wuhan High Voltage Research Institute (WHVRI); along with standards development agencies such as the Association of Edison Illuminating Companies (AEIC) and Insulated Cable Engineers Association (ICEA).
Think about life's little and big moments that happen every day and the role power plays in those moments: emergency surgery for a loved one, lighting a field for that nighttime Little League game or soccer tournament, cooking breakfast for your children, preparing to pitch that next big piece of business, holding a Skype chat with a friend many miles away, pumping a village's first clean drinking water from a local well. Which are we willing to chance by overlooking the implications of short-term thinking regarding power grid materials and cables?
Cables form a small percentage of a total power system's cost, and insulation and jacketing materials represent an even smaller percentage. Is it worth the risk to compromise system reliability in the long term by not investing in the best materials and cables in the near term? The need for sustainable power infrastructure for new and rehabilitated, aging systems will continue to grow globally. Whether using traditional or renewable energy resources, all power systems need cable for transmission and distribution. Cable must be reliable over a long period to satisfy a positive outcome for each utility's investment and to manage costs and confidence for consumers. Collaboration among materials suppliers, cable manufacturers and utilities is paramount to sustainable power system maintenance and growth. Materials suppliers must collaborate with cable manufacturers to deliver to utilities the value proposition that quality materials and the best manufacturing practices are essential to quality cable construction. Utilities must stay abreast of new material developments so they can insist that the cables they specify meet the strictest standards for long-term performance and reliability. All sides must consider external factors that affect cost so the entire value chain is financially secure to continue innovating. Providing cables with the best materials, manufactured to global standards, is the best bet for protecting the long-term investment of every power system. Quality materials and cable standards matter.
About the author: Damien Polansky is associate director of electrical infrastructure at Dow Electrical & Telecommunications.