Powerlines - Beckwith Electric Co, Inc. - Services and Products for Electric Power

Much of the new generation capacity installed in the next millennium will be accomplished through the construction of IPP (Independent Power Producer) generating facilities. These facilities can be small, dispersed generating units, or large capacity plants owned and even operated by non-utility personnel. Many of these dispersed generating units will be at smaller industrial and commercial facilities and operating in parallel with the utility system to reduce energy cost through load sharing or "peak shaving." These generators are typically connected to the utilities' distribution or subtransmission system. This article discusses the protection requirements to interconnect these generators to utility systems, as well as methods to reconnect these generators after interconnect protection tripping. The Beckwith Electric M-3520 Intertie Protection System, part of the IPS (Integrated Protection Systems®) line of products, offers an array of functions to meet these application needs.

Dispersed IPP generators need to be protected not only from short circuits, but also from abnormal operating conditions. Many of these abnormal conditions can be imposed on the IPP generator by the utility system. Examples of such abnormal conditions are: overexcitation, overvoltage, unbalanced currents, abnormal frequency and shaft torque stress due to utility breaker automatic reclosing. When subjected to these conditions, damage or complete generator failure can occur within seconds. Machine damage due to these causes is a major concern of IPP generator owners.

Utilities, on the other hand, are generally concerned that the installation of an IPP generator will result in damage to their equipment or to the equipment of their customers. Small dispersed generators are connected to the utility system at the distribution and subtransmission level. These utility circuits are designed to supply radial loads. The introduction of generation provides an unwanted source for redistribution of both load and fault current, as well as a possible source of overvoltage. Islanded operation of dispersed IPP generation with utility loads external to the IPP site is generally not allowed. One reason is because the utility needs to restore the outaged circuits and this effort is greatly complicated by having islanded generators with utility loads.

Protection requirements to connect an IPP to the utility grid are usually established by each individual utility, or in some cases, jointly developed with the IPP owner. These standards generally cover smaller generators. Larger generators are reviewed on a case-by-case basis and are usually connected to the utility's transmission system. These larger IPP generators do not typically employ specific interconnection protection because they are integrated into the utility protection system itself. Smaller IPP generators connected to the utility's subtransmission and distribution systems require interconnection protection.

Typically, interconnection protection for these generators is established at the point of common coupling between the utility and the IPP. This can be at the secondary of the interconnection transformer as illustrated in Figure 1, or at the primary of the transformer, depending on ownership and utility interconnect requirements.

Generator protection is typically connected at the terminals of the generator (Figure 1) and provides detection of: o generator internal short circuits; o abnormal operating conditions (loss of field, reverse power, overexcitation and unbalanced currents).

Generally, for dispersed generators, it is the responsibility of the IPP owners and their consultants to select the level of generator protection they believe is appropriate.

The functional levels of interconnection protection vary widely depending on factors such as: generator size, point of interconnection to the utility system (distribution or subtransmission), type of generator (induction, synchronous) and interconnection transformer configuration. As shown in Table 1, specific objectives of an interconnection protection system can be listed, as well as the relay functional requirements to accomplish each objective.

The most basic and universal means of detecting loss of parallel operation with the utility is to establish an over/underfrequency (81O/U) and over/undervoltage (27/59) "window" within which the dispersed generator is allowed to operate. When the dispersed generator is islanded from the utility system, either due to a fault or other abnormal condition, the frequency and voltage will quickly move outside the operating window if there is a significant difference between load and dispersed generator levels. Figure 2 shows this protection.

If the load and generator are near a balance at the time of separation, voltage and frequency may stay within the normal operating window and under/overfrequency and over/undervoltage tripping may not take place. If this is a possibility, then transfer trip (TT) using a reliable means of communication may be necessary.

Small synchronous machines are typically so overloaded after the utility substation breaker trips that their fault current contribution is very small. For these small generators, the detection of loss of parallel operation via 81O/U and 27/59 relays is all the interconnection protection necessary.

The larger the dispersed IPP generator, the greater is the chance that it will contribute significant current to a utility system fault. For this situation, fault backfeed detection in addition to loss of parallel operation protection is provided. Figure 2 indicates typical fault backfeed protection.

Unbalanced current conditions caused by open conductors or phase reversals on the utility supply circuit can subject the dispersed generator to a high level of negative sequence current. This high negative sequence current results in rapid rotor heating causing generator damage. Many utilities provide the protection against these unbalanced currents as part of the interconnection protection package using a negative sequence overcurrent relay (46). To provide protection for phase reversals caused by inadvertent "phase swapping" after power restoration, a negative sequence voltage relay (47) is also used. These functions are shown in Figure 2.

Some interconnection contracts between a dispersed cogenerating unit and the utility prohibit the generator from providing power to the utility. The cogenerator provides power solely to the local load at the generating facility and reduces utility demand charges by "peak shaving." Utilities frequesntly install a directional power relay (32) to trip the generator if power inadvertently flows into the utility system for a predetermined time in violation of the interconnection contract. Figure 2 illustrates this type of abnormal power flow detection.

Once the dispersed generator has been separated from the utility system, after interconnection protection operation, the intertie must be restored. Two tripping/restoration practices are widely used within the industry. The first restoration method is used in applications where the generation at the generating facility does not match the local load. In these cases, interconnection protection typically trips the generator breakers. When the utility system is restored, the dispersed generator is typically automatically resynchronized. Many utilities require a synchrocheck relay (25) at the main incoming breaker to supervise reclosing as a security measure to avoid unsynchronized closure. The synchrocheck relay is generally equipped with dead bus undervoltage logic to allow reclosure from the utility system for a dead bus condition.

The second restoration method is used where the dispersed generator roughly matches the local load. In these cases, the interconnection protection trips the main incoming breaker (breaker A) as illustrated in Figure 2. To re-synchronize the facility to the utility system, a more sophisticated synchrocheck relay is required which not only measures phase angle but also the slip frequency and voltage difference between the utility and the dispersed systems. Typically, such relays supervise manual and supervisory reclosing.

If the predictions of industry experts come true, interconnection protection will have renewed importance in the next millennium. Properly designed interconnection protection, such as the Beckwith Electric M-3520 Intertie Protection System, should address the concerns of both the dispersed IPP generator owner as well as the utility.

The M-3520 Intertie Protection System has a number of features that make it an ideal choice for interconnection protection of IPP generators-the most important being user-selectable functionality, self-diagnostics, communications capabilities and oscillographic monitoring. As I pointed out, interconnection protection functionality varies widely with generator size, point of interconnection to the utility system, type of generator and configuration of interconnection transformer. These variables make the user-selectable ("pick and choose") functionality of the M-3520 an important feature. The M-3520 can be purchased as a protection system or as a base system with optional protective functions that can be added to either system. This feature allows the specific configuration of the relay to be controlled by the user rather than the manufacturer and keeps the cost proportional to the level of functionality required.

Interested? For more information, contact Beckwith Electric at (727) 544-2326 or e-mail at marketing@beckwithelectric.com.

All Beckwith Electric protective relays incorporate several self-checking routines that continuously monitor critical functions. When an internal fault is detected, the relay safely removes itself from service and closes the diagnostic contact. However, these self-test functions cannot determine the integrity of a status input or trip circuit, nor detect small problems in CT or VT circuits. To verify the integrity of these circuits, we recommend routinely checking the relay's metering during normal operation and performing the diagnostic test procedure during outages. The output trip circuits can be verified by exercising the output relays and checking the external trip circuits for proper operation. This combination of internal self-diagnostics, input verification, and output testing assures that the relay is ready to protect your system. This maintenance should be performed according to the schedule as required by your company. Another point for customers with our M-0420 and M-0430 relays: we recommend periodically reseating the relay in the draw-out case. This prevents a layer of insulating silver oxide from fouling the case contacts.

One of the most useful and often overlooked diagnostic feature of our relays is the oscillographic recorder. With the recorder, up to 170 cycles (96 cycles in the M-0420 and M-0430 relays) of pre-fault input waveforms can be recorded automatically. The recorder may be triggered manually or by the operation of any output or input combination chosen by the user. Once triggered, this waveform data can be easily transferred from the relay using the IPScom® Communications Software. The waveform may then be analyzed using the available IPSplot® Oscillograph Analysis Software. The resultant data can be a valuable tool in determining the root cause of a relay operation.

If periodic functional testing is desired, consider that a single-phase or even a three-phase test set cannot duplicate system conditions for a relay which has 7 current inputs and 4 voltage inputs. Consequently, the technician has to disable or alter the setpoints of other functions to prevent interference with the function under test. This could result in the relay being placed back in service with a critical function accidentally disabled. To minimize this possibility, use the IPScom software shipped with your relay to save the relay's data file before testing, then write the same file back to the relay after testing. This practice can dramatically reduce the possibility of setting errors while also providing a convenient record of "as found" settings.

Successful functional testing of these relays involves a few steps. First, study the functional description from the relay instruction book (usually found in Chapter 2), carefully noting any special features. Second, connect the relay exactly as it will be connected to the system. Third, isolate the function under test with the IPScom software's configuration screen. Fourth, apply the nominal quantities and check the metering using the IPScom software's secondary metering screen. Finally, apply the test quantities and check your results. If the results are not satisfactory, check the secondary metering screen again with the fault quantities applied. If incorrect, check connections and inputs; if correct, check the function logic description and testing instructions.

By performing this routine maintenance as required, you are helping to ensure the integrity and reliability of the protective relay. For assistance, Beckwith Electric's service engineers are a phone call away at (727) 544-2326.

Screen from IPSplot® Oscillograph Analysis Software showing a differential trip. The vertical variegated line in center indicates the breaker tripping and subsequent Beckwith relay operation. The suspected cause is a wiring problem in their CT circuit.

Beckwith Electric recently hosted the IEEE (Institute of Electrical and Electronics Engineers) Florida West Coast Section's monthly meeting on Thursday, August 24th. Over 26 attendees were given a plant tour and attended a presentation on adaptive volt/VAr management.

Mark Dixon, Manager of Autodaptive® Systems, reviewed Beckwith Electric's Autodaptive® Volt/VAr Management System and the impact it can have on overall system efficiency. Mark explained that distribution system losses are significantly reduced by managing VArs in the distribution system through coordinated adaptive control of capacitor controls and LTC controls. He discussed Beckwith's Autodaptive solution and how it provides an innovative means to achieve a reduction in losses, reduced tap change operations, and reduced maintenance. Mark then covered an economic evaluation model that approximates the typical financial impact to a utility using an Autodaptive Volt/VAr Management System.

Beckwith Electric would also like to commend the FWCS (Florida West Coast Section) Chapter for receiving the 1999 Large Chapter Power Engineering Society (PES) Award. This is the second time in the chapter's history that they have been honored with this award (the first time being in 1991). This award demonstrates that the FWCS is dedicated to offering outstanding support for its members. The FWCS Chapter serves over 2,300 members in twelve counties. Congratulations!

The Protection group develops protective relays such as the
M-3425, M-3520 and M-3310 Integrated Protection Systems.
L-R
Joel Bryant, Design Engineer
Wai-Man Yu, Senior Software Engineer II
Gary Sun, Senior Software Engineer II
Steve Walker, Senior Software Engineer II

The Products group is responsible for upgrading, modifying,
and supporting all released products.
L-R
John Galanos, Manager of Product Engineering
Tom Sweet, Senior Engineer I
David Seeger, Senior Engineer I

The Control group is responsible for the newest line of controls at Beckwith Electric Company-the Autodaptive® line-including the M-2501A Autodaptive Capacitor Control, M-2667 Autodaptive Transformer Control and M-2600 series of Autodaptive Regulator Controls.
L-R
Sitting:
Drew Craig, Manager of R&D, Control
Lawrence Bach, Senior Software Engineer I
Carl Terrier, Senior Software Engineer II
Standing:
John Nesselhauf, Senior Software Engineer II
Mike Lian, Senior Software Engineer II

Amado M. Peña Jr.'s art captures the essence of the Southwest. Peña, a mestizo of Mexican and Yaqui Indian descent, was born in 1943 and raised in Laredo, Texas. He earned B.A. and M.A. degrees at Texas A & I University in Kingsville, Texas and was an art teacher in Texas public schools for sixteen years. Peña's work depicts Hispanic and Native American figures and his work has been exhibited throughout the Unites States.

Peña is known for his humanitarian efforts, and his fund-raising activities have benefited charities such as the March of Dimes, Juvenile Diabetes Foundation, Native American Rights Fund and the Mexican American Legal and Educational Fund. The Amado and JB Peña "Art Has Heart" Foundation, established in 1994, provides opportunities for low and modest income students in Texas, New Mexico, Colorado and Arizona to further their education in the arts.

According to Peña, "I feel blessed having seen and touched the beautiful things that speak so proudly of who we are. Our gifts to the world are our history, our art."

For more information on the artist and his work, contact the Peña Studio Gallery at 235 Don Gaspar Ave., Santa Fe, New Mexico, 87501; call 1-888-220-Peña; e-mail to penagallery@earthlink.net or visit the Web site at www.penaofficial.com. A new Web site is expected to be launched this fall at www.penagallery.com.

Mestizo Series: Caballitos de los Americas (Poster)
© Amado Peña Studio-Gallery

Beckwith is expanding in several areas of operation to keep up with advancing technology and the demands of growth. This expansion includes the addition of new equipment on the factory floor, more automatic testing units in the Quality Assurance Department, and the augmentation of office, lab and production space.

In July, a new wave solder machine was put into operation on the production floor-the SOLTEC Delta Wave soldering machine that has its own computer and software. The older soldering machine had to be manually adjusted to accommodate the different-sized boards for each production run and did not meet the needs for the newer style boards.

"This new machine yields a better product," says Tom Manley, Manufacturing Engineer. The computer that runs the machine stores individual profiles for each board design, so a few clicks of a mouse can automatically adjust the machine to precise settings required by a specific board style. Production yields have also increased dramatically over the old process. "Boards can go through the machine, be checked and corrected in only five minutes, whereas the old process sometimes took as long as 45 minutes for each board," says Tom.

Charlie Finn (Production Supervisor), Dan Farhadi (Assembler) and
Tom Manley (Manufacturing Engineer) inspect board soldered
on new wave-soldering machine.

The QA (Quality Assurance) Department has expanded its production testing capabilities by adding new PC based software-driven test systems. The production test department utilizes three three-phase automated test systems which allow them to accurately test more units in less time. For example, with our new M-2001B Digital Tapchanger Control line- With the old testing equipment, QA only had the ability to test one unit at a time. "With the new test routine, developed by Wayne McAttee, Test Engineer, we can test up to six M-2001B units at one time. The automated test routine accomplishes the comprehensive tests in one-third of the time it took to conduct a manual test, factor in the six units per test, that is a significant improvement," says Dana Bergeron, QA Supervisor. "This system allows us to test our products faster and more efficiently."

QA is currently using the automated test systems to test all digital based products and will soon expand the capability to test the solid state-type products. When this happens, all Beckwith products will be tested on the same platform, making the production test process more robust, efficient and repeatable while making testing equipment easier to maintain.

After a tornado destroyed the Beckwith Electric facility in October 1992, Beckwith recovered by building a 48,320 square foot building and resuming normal operations. In the new building, approximately 7,000 feet on the second floor was left unoccupied or used as storage space. Recently, Beckwith has launched an expansion process to develop that unoccupied space. Construction is currently underway to develop that area and create additional offices and conference space to support the increasing manpower employed by Beckwith.

The development of this space also allows the expansion of the R&D (Research and Design) Lab-the lab will be twice its current size. Three technicians have recently joined the R&D Lab and additional equipment such as a new Omicron testing system has been purchased. With the increased manpower and additional equipment, R&D can take advantage of the extended space to double their capabilities for testing and development.

R&D Lab Technicians (L-R): Glen Ferrall, Kokheng Lim,
Joseph Radawec and Cyrill Lobo

Another area that will benefit from the development of this unoccupied space will be the Manufacturing Department. Part of the space will be used to locate a second SMT production line. By adding a second production line, Beckwith can be fully redundant by March 2001. This means that if one production line goes down, a backup will be in place to prevent production delays.

Bob Ahearn, Director of Manufacturing says, "Beckwith's intent is to grow a production facility that keeps pace with state-of-the-art electronics assembly, and this development is proof of commitment to that intent."

This summer has been an exciting one for the Beckwith Electric Company Web team. On August 17, we launched our redesigned Web site at www.BeckwithElectric.com. Encased in a clean, new design, the site has consistent navigation and better organization, along with more content.

The home page of the Web site contains Electrifying News that is updated frequently. The site has seven main sections that can be reached from any page of the Web:

On the bottom of each page, the navigation consists of support links including Search, Contact Us, Subscribe, Site Map and Home. The site map, a new feature, shows the organizational structure of all the main pages in the site. Below the graphical navigation, you will find text links to each section.

Our much-requested Quick Reference Guide for Transformer and Regulator Control Replacements is now available online under Product & Solutions. The Document Center, formerly called the Information Center, is a central location for all of our documents.

A particularly colorful new section of our site is the world and country maps for locating your sales representative. These maps are found under both the Contact Us and Customer Service areas. In case you plan to visit us in Largo, Florida, we have joined forces with Mapquest.com to provide customized directions, maps and information on local venues.

The Beckwith Electric Web site will continue to grow with more product information, updates to existing features, and more documents. Feel free to share your feedback on the Web site by e-mailing me at webmaster@beckwithelectric.com.

Articles from Issue 32, September 2000 of Beckwith Electric's Powerlines.
Copyright 2000. All rights reserved. Reproduction of the whole or any part of the contents without written permission is prohibited.

Issue 32 - September 2000