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The incorporation of these and other HBM data acquisition systems allows for the successful integration of new high-voltage grid systems and components, as well as the upgrading of legacy systems, with added safeguards for continuous, uninterrupted power service. HBM data acquisition systems are also used to support next-generation "Smart Grid" technology development. As system concepts are developed, a growing need exists for the testing of supporting high-voltage component parts, such as switchgear devices, transformers, surge arrestors, cables, isolators and other products, to support newly developed infrastructure. R&D test laboratory requirements for "Smart Grid" technology are also increasing. In addition, with the advent of a new and more efficient infrastructure for energy delivery, the formal establishment of new testing standards and procedures is also likely, bringing with it new applications for HBM high-voltage data acquisition technologies.
Circuit-breaker Interruption (Current Zero) Detection and Monitoring
Traditional circuit breaker systems operate on the premise of electrical contacts moving away from one another, thereby creating an electrical arc. Another high-voltage testing area for HBM is the measurement of interruption phenomena affecting breaker performance and operation, a term known as circuit zero (CZ). CZ measurements are commonly used as a research tool to help better understand and improve the descriptive mathematical model of the electric arc itself, while identifying dominant parameters for successful current interruption, such as pressure, temperature, ion density, plasma flow and other parameters, leading to circuit breaker design improvements and the achievement of greater interruption capability.
Circuit-breaker manufacturers often rely upon third-party test laboratory services for acceptance testing. The external test house acts as a credible, independent authority between buyer and seller, verifying product performance according to published specifications, with a buyer identifying individual specifications of interest for verification. While international testing standards for circuit-breaker final products are well-established, CZ testing standards can vary. As a result, the Arnhem, Netherlands-based KEMA High-Power Laboratory, one of the leading global experts in high-power acceptance testing, has established its own fully dedicated CZ test program.
To conduct CZ testing, use of a fiber-optic isolated digitizer with particular performance attributes, such as the HBM GEN 6600 HV, is recommended. The digitizer should ideally be placed as close as possible to the test article, in order to minimize required analog cable lengths and to ensure best results. A suitable fiber-optic digitizer must also be able to deliver signal quality conditions for safe performance, as can be found within the existing KEMA system. Among the necessary system performance attributes, high dynamic input range is important, as currents in the order of 100 mA should be measured immediately following the interruption of many tens of kA of short circuit current. While the main frequency range of the application is typically only 50 or 60 Hz, other relevant processes occur on a sub-microsecond scale, making required bandwidth another key specification, as well as vertical resolution.
As the system must also be able to reliably operate, undisturbed and uninterrupted, in the presence of naturally occurring transients, electromagnetic field immunity is also important. Further immunity against the fast or transient electrical events that can arise within both current and voltage during the switching progress is also critical. High-voltage circuit breaker test laboratory environments tend to see the most electromagnetic interference, as the highest voltages and currents occur simultaneously, also using the greatest amount of energy.
A typical acceptance test is designed to verify proper system operation under the most severe product operating conditions within a high-power test laboratory. A system's ability to pass under the worst possible conditions implies that its operation under less severe conditions, such as medium- and low-voltage tests, would not cause significant problems, as components are exposed to less stress and less energy is used to perform the testing itself. The HBM GEN 6600 HV fiber optic digitizer was fully tested by KEMA and passed at all levels of acceptance testing, including under extreme conditions, making it a viable option for high-voltage or CZ-related testing requirements.
A copy of the report may be downloaded from: www.hbm.com/power under the Current Zero section.
Switchgear Testing
Another rapid transient electrical application exists in the area of switchgear testing. This application calls for the use of equipment that can effectively measure low-, medium- and high-level energy values on an as-needed basis, with each requiring different isolation capabilities. The system must also be able to offer accurate sequencing and timing control, so that in case of a failure within one segment, such as a short circuit due to component breakdown, the rest of the grid may be protected by disconnecting the failed segment and interconnecting remaining, active segments. Because of its complexity and wide energy measurement ranges, specific hardware and software must be used to produce accurate, safe and reliable test results.
Within this type of testing, high currents of up to hundreds of kA must be interrupted, while high voltages of up to several hundred kV are still present. Thus, hardware must have isolation, excellent electromagnetic field immunity and offer battery-powered operation, with supporting software that features strong data integrity, repeatability and optimal user test efficiencies. A typical high-power switchgear test is ideally conducted using a completely battery-powered and fiber-optic isolated digitizer to obtain optimal signal quality, with appropriate voltage protection for personnel and equipment. Successful switchgear testing requires the use of a data acquisition system, fiber-optic isolated digitizer, test sequencer and supporting analysis software. Due to the complexity and dangers associated with this type of testing, it is recommended for a customer to source all of these components from a single manufacturer, to ensure seamless system compatibility, experienced technical support and necessary system calibrations.
The HBM Genesis HighSpeed data acquisition system, previously noted for use within one-shot lightning strike monitoring applications, has been successfully used to support high-voltage switchgear testing. In addition, the 6600 MV fiber optic digitizer system offers an isolated power supply and small battery setup for safe and effective medium-voltage testing requirements. For high-speed test sequencing, the fully fiber-optically isolated HBM BE3200 is ideal for switchgear applications, due to its fully user-synchronized timing pattern to the main generator, either via the external mains or derived from an internal timer, and application specific extensions. Both hardware and software associated with HBM switchgear monitoring system components are fully compliant with international high-voltage testing community regulatory and safety standards, with proven software designs and algorithms developed according to globally accepted practices. Customized commercial software packages are also available upon request.
Acknowledgements for this article
By Michael Hoyer, Applications Engineer, HBM, Inc, Marlboro, Massachusetts, USA
Carlos Mata, Ph.D., Subject Matter Expert, ESC, Kennedy Space Center, Florida, USA
Molly Bakewell Chamberlin, President, Embassy Global, LLC, Buffalo, New York, USA
For further information about these and other HBM products for rapid transient electrical applications, view website: www.hbm.com Refer to page 143
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The overall frame size is 202 x 120mm, which can be equipped with grey coloured elastomer inserts to provide IP54 cable sealing, can also accommodate cables and tubes up to 75mm diameter in a variety of cable sizes and grouping combinations. Standard frame plus insert assemblies can be provided to cover maximum size cable arrangements of 2 cables up to 75mm diameter, or one cable of 75mm and four of 34mm diameter, and a third arrangement of eight cables of 34mm diameter. In all cases, cables of lesser diameters can be accommodated, together with cables incorporating pre-assembled terminations.
The ease of achieving both frame and cable run installations at bulkhead junctions, together with the time saving achieved, makes these products suitable for a wide range of general engineering and commercial applications. This covers control panels up to full machine building projects as well as transportation equipment involving trams, trains and marine projects. The compact, clean lines are also compatible with requirements for commercial building installations including offices, schools and hospitals etc.
The elastomer inserts available for the KEL 183 range include split versions to simplify cable layout modifications or cable additions, while ensuring a minimum of on-site work being required. The inserts can be supplied pre-formed for clamping and sealing cable O/D sizes of 34-44mm, 44-54mm or 54-64mm respectively. A pre-formed insert is also available for cable sizes 64-75mm diameter, together with a blind insert which can be incorporated to accommodate future cabling requirements. This can be cut as required (cable diameter minus 10mm to achieve IP54 sealing) to act as a mixed, variable diameter insert for varied individual cables up to 55mm in size.
Both the Polyamide frames and elastomer inserts are halogen and silicone free and achieve flame class UL-94 Vo with self-extinguishing qualities. The temperature ratings are -40°C to +140°C for the frames and -30°C to +90° for the elastomer inserts.
For further information, e-mail: info@buttkereit.co.uk or view website: www.buttkereit.co.uk Refer to page 176
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