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Issue 37 - December 2001
David Brooks Promoted to Director of Manufacturing Beckwith Electric Co., Inc. is pleased to announce that David Brooks has been promoted to Director of Manufacturing. He has been with Beckwith Electric since 1987. As the Quality Assurance Manager, David played a key role in providing quality products and services to our customers. Now, as Director of Manufacturing, he is responsible for the supply chain management, production engineering and manufacturing operations.
David has a Bachelor of Arts in Business Management from Eckerd College in St. Petersburg, Florida, as well as an Associate of Science in Quality Control Management from New Hampshire Vocational Technical College. He has also trained in Six Sigma Techniques. David is a member of the American Society of Quality Control and the IEEE.
David Martinez is the newest member of the Board of Directors for Beckwith Electric Company. He is an engineer with Sandia National Laboratories in Albuquerque, New Mexico, a sister lab to the Los Alamos facility and now owned by Lockheed Martin. Sandia develops satellite monitoring hardware and electronics. Previously David worked for the electronics firm EG&G, an Albuquerque-based contractor for the Department of Energy, where he was a design engineer. David has a Bachelor of Science degree in architecture from the University of New Mexico and has taken additional classes in engineering and architectural engineering. David's wife, artist Chao Ming Ting of Taipei, Taiwan, introduced him to Robert Beckwith ten years ago, and they have enjoyed a friendship since. We welcome David to Beckwith Electric's Board of Directors.
Interconnection Transformer Winding Arrangement Implications on IPP Protection By Wayne Hartmann, Manager, Application Engineering, Protection and Protection Systems The increased number of IPP (independent power producer) interconnections for peak shaving and power continuity applications on distribution feeders has increased the interest in, and application of, IPP interconnection protection. When operating IPP generation, known as DG (dispersed generation), in parallel with the utility, the applied interconnection transformer winding arrangement has an effect on what protection is applied to provide utility ground fault detection, and the subsequent separation of the IPP's generator from the utility. This protection and separation of the IPP's DG from the utility is required, so the IPP does not continue to feed into a utility ground fault after the utility has tripped an upstream substation circuit breaker or a line fault-clearing device, such as a recloser. Clearing a utility ground fault from all sources, including any IPPs on the feeder, is necessary to extinguish the arc. After the arc is extinguished, typically an automatic reclosing sequence (by the breaker or recloser) is applied to test the feeder; it then remains closed if the fault was transient in nature. After the reclosing cycle is deemed successful (the reclaim timer expires), any IPPs on the feeder are then clear to attempt parallel DG operation with the utility. The interconnection transformer winding arrangement can be defined as the type of winding that is applied to the primary, or utility side, and the secondary, or IPP side, of the transformer. Several winding arrangements are possible, all requiring an understanding of the impact each arrangement will have on the utility's protection, the IPP's protection, and power system operation. Possible IPP interconnection transformer winding arrangements are shown in Figure 1.
Figure 1: Possible IPP Interconnection Transformer Winding Arrangements If the generation at the IPP site is retrofitted into the facility, the usual transformer arrangement is delta-wye (grounded). This arrangement is typically chosen to provide isolation for the utility for ground faults in the IPP's facility, and to supply a ground source for the IPP facility. Examining each of the interconnection transformer arrangements, and placing
ground faults on the circuit illustrated in Figure 2, the pros and cons
of each may be explored. Figure 2: Ground Fault at Various Locations on Distribution System with IPP Delta-Delta Note: First winding is utility primary, second is IPP secondary The first three transformer winding configurations provide a focus on interconnection protection, (and all configurations provide an ungrounded utility primary winding,) but they require a different utility system ground fault protection method than the last two transformer winding configurations, which provide a grounded utility primary winding. When employing a grounded utility primary winding, if the utility opens its substation breaker or line recloser, the IPP's DG can backfeed the distribution line, and a ground current is available at the interconnection transformer which is detectable by employing ground overcurrent elements. On the primary (utility) side of the transformer, a transformer neutral ct may be the source for directional or non-directional ground current protection (51N or 67N). On the secondary (IPP) side of the transformer, phase undervoltage elements may be applied to detect utility ground faults, as the resultant voltage drop is measurable across the interconnection transformer while the utility has not yet cleared the ground fault. The measured secondary (IPP) side voltage will also drop if the IPP is sourcing the fault. For delta secondaries, in addition, voltage controlled or restrained overcurrent elements (51VC and 51VR), sometimes directionalized for greater sensitivity (67 supervision) may be employed. For grounded wye secondaries, ground overcurrent (51N) or directional ground current (67N) elements may be employed as the zero sequence current commutates across the grounded wye-grounded wye transformer. When employing an ungrounded utility primary winding, if the utility opens its substation breaker or line recloser, the IPP's DG can backfeed the distribution line. As the ungrounded delta winding does not commutate zero sequence current to the secondary, conventional ground relays applied on the primary neutral will not detect ground fault current. This is because the ungrounded winding does not provide a ground source. The phase and ground protection on the secondary (IPP) side of the interconnection transformer will not be able to detect and clear the utility feeder ground fault supplied by the ungrounded source. Fortunately, there are methods employing voltage protection that can detect a ground fault supplied from an ungrounded source. To detect and clear the utility ground feeder ground fault sourced from
the ungrounded primary (utility) side winding, a protection scheme is
applied that uses one of two options: 2) Over/under voltage of a single phase measured line- to- ground voltage on the utility's system (primary side of the interconnection transformer): This method takes advantage of the fact that when a phase of the delta system is grounded, the grounded phase falls to zero volts, as it is now the ground reference. The other two phase voltages rise to line-to-line values. The resultant voltage across a single line-to-ground connected potential transformer will be a detectable undervoltage or overvoltage (1.73 times the line-to-ground secondary value) depending on which phase has the ground fault. When used together with the other protections typically employed for
IPP interconnection protection, we have two basic schemes, one for grounded
interconnection primary (utility) windings, as shown in Figure 3, and
one for ungrounded interconnection primary (utility) windings, as shown
in Figure 4. Figure 3: Typical IPP Interconnection Protection Application - Grounded Interconnection Transformer Primary (Utility) Winding Figure 4: Typical IPP Interconnection Protection Application - Ungrounded Interconnection Transformer Primary (Utility) Winding To summarize, the interconnection transformer winding arrangement applied has implications on the protection utilized at the IPP's facility; it also has possible impacts on distribution system protective elements. There is no single "best" connection type or universally applied arrangement. Attention must be paid to the winding and utility side grounding so the proper IPP ground fault backfeed protection may be applied and other coordination issues can be realized. References:
Boxing in Quality: The Shipping Department hard at work As part of Beckwith Electric's ongoing commitment to quality, our shipping and packing procedures are designed to get our products safely to you in a timely manner. The procedures are built around two product types: small or medium sized units, such as our relays, controls, and panels; and custom or large units, such as the Beckwith Systems Engineering (BSE) cabinets. Our packing is both cost-effective and environmentally friendly by reducing the amount of packing materials.
Beckwith Electric held its third annual Relay Seminar, October 14-19 in Clearwater, Florida. Forty participants from across the U.S. and Mexico attended the seminar, which included intensive training in generator, power plant transformer and intertie protection. This seminar builds the background needed to understand the complex subject of generator, power plant transformer and intertie protection, even for those with a limited knowledge of protective relaying. The instructors were Charles Mozina, Applications Manager, Protection Products and Systems; Dr. Murty V. V. S. Yalla, VP of Research and Development/Engineering; Wayne Hartmann, Manager, Application Engineering, Protection and Protection Systems; and Scott Cooper, Field Service Engineer. Rachael Herrera, Inside Sales Specialist, provided support on software applications.
The IEEE Transmission & Distribution Conference and Exposition in Atlanta last month was well-attended-proving both busy and successful for Beckwith Electric. An average of 70 people were in attendance at each of the three technical paper presentations and three info sessions provided by Mark Dixon, Manager of Market & Project Development for Control Products & Systems, Tom Jauch, Manager of Application Engineering for Control Products & Systems, and Chuck Mozina, Applications Manager for Protection Products & Systems. Information from these sessions is available on our Web site at www.beckwithelectric.com under the Document Center link.
Articles from Issue 37, December 2001 of Beckwith Electric's Powerlines. |
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"I'm
excited about the future of Beckwith Electric," says David. "The
challenges are many and opportunities are great. As we continue to grow,
we are confronted with continuous change in technology, coupled with producing
product on demand. We utilize new technology in our products and in our
manufacturing processes. The most important element in meeting our goals
is our people. We have a great group to work with. Our well-trained and
skilled work force continues to work at optimizing our processes."
The
smaller units are packed by our shipping clerk, Jeff Hill. Due to the
varying sizes of our products, Jeff uses basic cardboard boxes and a chemical
foaming mix from the Sealed Air Corporation to create custom-fit containers.
The harmless chemicals spray from a nozzle into the boxes, creating a
lightweight foam, and fill in the gaps, thus preventing the products from
shifting during shipment. Damon Williams, Production and Inventory Control
Supervisor, says, "The process allows for an infinitely variable
package and reduces costs by allowing us to create a custom box from a
standard box for each order." The products are individually wrapped
in a protective material, such wadding or plastic sheeting. If multiple
units are being shipped, soft packing is placed between each unit for
additional cushioning. The boxes are sealed with heavy-duty staples. Jeff
packs small accessory items, shipping alone, in padded envelopes or in
small boxes with recyclable peanuts.
At
the exposition, three people won Handspring™ Visor™ Deluxe handheld
computers from Beckwith Electric's business card drawings. The winners
are: Allan Desserre, Transmission Station Projects Engineer at Manitoba
Hydro in Canada, Alan Fazio, Engineer with Lake Region Electric Cooperative
in Pelican Rapids, Minnesota, and Jerry Garrett, Process Specialist in
Electric Distribution with Duke Power. Congratulations to all! The Handspring
Visor is currently being used as the HMI (Human/Machine Interface) for
all of Beckwith Electric's Autodaptive® controls. Software is currently
being developed for the Handspring Visor to interface with the newly introduced
M-3410 Generator/Intertie relay. Watch for its release.