Following Protective Relaying Trends

Transmission & Distribution World February 2000

By Chuck Newton, Automation Editor

As many readers will affirm, digital relays have been mainstream products for a few years now in what had been the most technically conservative engineering section of a conservative industry. However, it appears that not all relays we purchase now and in the future will be digital units. Why not?

Not the Universal Solution

Digital relays continue to account for an increasing share of all new relay purchases. This does not mean that we are casting aside electro-mechanical (e-m) relays. In fact, in North America e-m relays continue to account for 22% to 46% of new-use purchases, depending upon application. In Western Europe, a 15% to 25% rate of new e-m relay purchases remains. As funding permits, Eastern European utilities continue to buy a new generation of e-m relays almost exclusively.

How can this be? Why would relay engineers continue to specify, buy and use single-function e-m relays, when, for about twice as much money, they can obtain three-to-five times the functionality in a single digital relay?

To obtain some answers to these questions, I met with Tony Giuliante, president of ATG Exodus and a career-long participant in, and observer of, trends in the protective-relaying industry.

Giuliante indicated that e-m relays are continuing to be purchased for several applications. He suggested three principal reasons for utilities continuing to specify and buy older e-m units.

"First, some of the older engineering consulting firms have drawings from previous jobs and may convince utility clients to stay with a proven choice," Guiliante said. "Secondly, to use digital units, the utility must have a base of personal computers and computer-knowledgeable field people. Thirdly, and perhaps most importantly, there are still many single-function requirements for relays. For many of these single-function applications, e-m relays continue to fit the requirement adequately and economically," he added.

According to Giuliante, even smaller utilities have a requirement for obtaining and understanding fault records and the information they contain. Hence, the smaller utilities also are moving into the digital-relaying era. Secondly, he said that in the transmission area, the move to digital relaying is pervasive, and for good reason. It is in the transmission area where digital units really shine. Each digital-relaying function set is an integration of multiple individual e-m relaying functions. This function consolidation helps optimize the performance of the bulk power system.

The Growing Need for Outside Services Providers

In North America, the most apparent need for outside relaying-related services is in the area of training and installation services. Western European utilities agreed with the need for training and installation, but they also were looking for help with commissioning, renovation and upgrade services. Eastern European utilities expressed nearly universal needs for setting studies and training services, closely followed by a need for protective systems design services.

Giuliante indicated that with downsizing "completed" in many large utilities, many T&D engineering staffs are pared below a nominal safe level, and there is a serious shortage of relaying engineers with 7 to 10 years of experience. For this reason, and the fact that he expects that relaying engineers will be asked to wear multiple engineering hats in the future, reliance on outside service firms with relay expertise will necessarily increase.

Key Issues and Trends for Relaying in the Next Year

Currently, the relaying industry is faced with several "front-burner" issues. According to Giuliante, this year's hot issue is "retrofit." This especially pertains to removing the first generation of solid-state relays - already 25 to 30 years old - because, for many, replacement parts are not available. "These older relays do not monitor their own condition and cannot self-test adequately. The present trend is to use dynamic relay-testing methods," Giuliante said. "Older utility developed methods and procedures still in use at many utilities for maintenance were developed in the period of 1955 to 1975 and are simply inadequate for today's relay technology. How to adequately test for the status of older relays is one part of the "retrofit" issue confronting the industry."

In closing, Giuliante added this observation: Up until the 1990's, manufacturers were faced with the challenge of customizing relay hardware to meet the needs of relaying customers. You could go through product catalogues and find hundreds of variations of basic relays. Today, with the advent of digital-relaying products, the burden of customization is shifting to the relay buyer. The utility, or industrial relay customer, has to design and implement the desired customized features for a particular relaying application using the software tools provided by the manufacturer. "That represents a major industry shift - and a challenge to today's utilities," said Giuliante.

What challenge, you say? Well, first of all, utilities are losing, not gaining, people with the right stuff to tackle this change. Secondly, solid-state units may need to be ramped up if any more serious outage incidents occur early in this new decade.