Cold War on Grid Failures

Consumers take power supply quality for granted, but the job of assuring it isn’t simple. Ensto’s cold shrink products make the task easier for power utilities.

Ten million kilometers, more than a dozen round trips to the moon: it’s the total length of electricity distribution networks in Europe. If generation plants are the heart of power systems and transmission the big arteries, distribution is the last mile, the maze of small vessels carrying nutrition to every single cell, about 260 million consumers. Big numbers mean big responsibilities to households and businesses. Given the large risks, operators make every effort to prevent grid failure, and promptly fix them when they happen. It’s not easy considering that almost half of distribution grids run underground, making repairs difficult and costly. That’s where reliability of components comes into play in the daily war on breakdowns.

Every 500 meters

“Cold shrink joints for medium voltage underground cables dramatically reduce failure rates by making assembly mistakes nearly impossible,” says Claudio Malpede, Sales Manager at Ensto. For this reason, he says, last year Ensto won tenders to supply accessories to Enel and Endesa, the biggest power utilities in Italy and Spain, respectively. To build underground medium voltage (MV) networks – which represent a significant share of distribution grids – operators use cables several hundred meters in length, connecting them in single lines. This requires specific electrical joints, which are also used for repairs. The durability of a joint depends heavily on the quality of installation. Until a few years ago the preferred technique was heat shrink – using a flame to make the insulation tube shrink around the cable. This approach is much prone to errors. Cold shrink technology has changed all this, making the same operation quicker, simpler and, what matters most, more uniform in the outcome.

Power utilities turn to cold

“To make a mistake installing an Ensto cold shrink joint you must try really hard,” says Malpede. Since all components of the joint are pre-assembled on only one integrated structure with spirals, the product is virtually foolproof, a feature that customers seem to appreciate. “In the last few years we turned to MV cold shrink joints for all our new installations,” says Roberto Bortolamasi, Technical Manager at Hera Modena, a utility serving 400,000 customers in northern Italy. “This technology halves installation times compared to heat shrink and makes the job easier, cleaner, and the outcome more reliable.” Reliability is what operators and consumers care most about, because every failure causes at least a short interruption of supply and repairs require complex and costly operations.

Time and money

“Fixing an underground cable usually takes one full day and can cost from a few hundred to 15,000 euros,” explains Bortolamasi. Permissions may be needed, inconvenience for traffic created, and monetary penalties imposed. In 2012, the Italian energy regulator imposed a total of 30 million euros in fines to low performers. Similar considerations also apply to cold shrink terminals which are used to connect ends of electric cables to substations. “With cold shrink products three terminals can be installed in less than an hour,” adds Bortolamasi. Time and reliability are even more critical in emergency cases. Network operators have special supply needs on a spot basis in the case of unplanned maintenance or grid breakdowns. In these cases, product availability and sharp delivery become paramount.

Emergency needs

“My company meets Enel’s local needs and we chose Ensto’s products because of prompt availability and timely delivery,” says Domenico Rotelli, Managing Director of S.A.I., an electric supply wholesaler covering Sicily.   Rotelli’s S.A.I. of Palermo holds inventories of Ensto products that are tapped by Enel in case of emergency. “This is typically the case between May and August,” he explains, when Sicily’s scorching summers push up power demand for air conditioning, increasing the load on the network. “I can expect delivery in ten days max – and that matters!” So the “cold war” on grid failures continues, and the aphorism about distribution networks remains ever true: The best repair is the one you don’t need to make because you chose the right material.

Author: Gionata Picchio