The September/October Issue of the Electrical Insulation Magazine has been released. Use the accordion headings below to explore this issue’s content, and visit the IEEE Xplore for full magazine access.
Medium Voltage XLPE Cable Condition Assessment Using Frequency Domain Spectroscopy
Ali Naderian Jahromi, Pranav Pattabi, John Densley, and Laurent Lamarre — Xplore Link
Dielectric Response Measurement on Service- Aged XLPE Cables: From Very Low Frequency to Power Frequency
S. Morsalin and B. T. Phung — Xplore Link
Novel Gases as Electrical Insulation and a New Design for Gas-Cooled Superconducting Power Cables
T. Stamm, P. Cheetham, C. Park, C. H. Kim, L. Graber, and S. Pamidi — Xplore Link
Dr. Ali Naderian
METSCO Energy Solutions
Cable Diagnostics Trends
This issue is focused on underground cable diagnostics. Therefore, I thought it would be appropriate to review the latest changes occurring in the cable diagnostics business. Underground cables are an important part of electric power transmission and distribution systems. The global market of the HV power cables is estimated to grow to $14 billion during 2020-2024.
On the other hand, as COVID-19 pandemic has put pressure on every part of each country’s economy and society, the need for maintaining reliable, uninterruptible, and sufficient electric power for a sustainable economic recovery is essential. Diagnostics and testing play a critical role to ensuring the reliability and forecasting the life of underground power cables.
The relevant IEC standards for AC cables are IEC 60502-2 for Cables 6kV–30kV, IEC 60502-4 for Cable Accessories 6kV–30kV, IEC 60840 for Cable & Accessories 30kV–150kV, and IEC 62067 for Cable & Accessories 150kV–500kV. These IEC standards provide limited guidance for testing and diagnostics. On the other hand, guides developed by IEEE ICC contain more detailed guidance for traditional and advanced diagnostics of power cables. I will discuss the IEEE documents in other relative sections.
The report published by EPRI in 2014, “Diagnostic Techniques for Underground Cable Systems”, provides an overview of existing and developmental diagnostic techniques for both polymeric and oil-impregnated cable systems. The Centre for Energy Advancement through Technological Innovation (CEATI) has recently published a report on “Advanced Cable Diagnostic Test Techniques for XLPE, HPFF and LPFF Cable Systems” that provides a practical guide for HV cable diagnostics.
Oil-Impregnated Paper Systems
There are numerous HV and MV oil-filled cable circuits with an average age of 60 years or older worldwide. These cables are generally reliable and have a long life. The main mechanisms of aging and failure of oil-impregnated cables are leak and corrosion, thermal aging, paper thermomechanical deterioration, metallic sheaths thermomechanical deterioration, and paper electrical aging. One of the challenges is to maintain the integrity of the oil-filled cables such as the pipe for High-Pressure Fluid Filled (HPFF) and the sheath for Self-Contained Fluid Filled (SCFF) cables against corrosion.
IEEE Std. 1425-2001, “Guide for the evaluation of remaining life of impregnated paper-insulated transmission cable systems”, is a decent document for diagnostics and condition assessment of oil-filled cables. Furthermore, CEATI developed a guide for “Transmission Underground Cable Reference Manual Maintenance” in 2014. This guide provides detailed procedures for both LPFF and HPFF cable oil leak tests such as PFT. It also covers maintenance testing such as anti-corrosion sheath tests, measurement of sheath bonding currents, cross-bonding check, partial discharge (PD) diagnostic test during the 1-hour AC withstand test, resistance measurement of the conductor, capacitance and dissipation factor, TDR, positive and zero-sequence impedance measurements, Dissolved Gas Analysis (DGA), jacket
withstand and insulation resistance, and dielectric insulation resistance measurements.
Extruded Dielectric Cables
In some of the developed countries, XLPE cable installation peaked in the 80s which has resulted in the average age of 40 years or more for the majority of MV XLPE cables. Similar to other MV and HV assets, underground cables and cable accessories are subject to electrical, thermal, mechanical, and environmental stresses during the lifetime. One, or a combination, of the stress factors cause degradation of the cable system that can lead to failure. The main mechanisms of aging and failure modes of extruded cables are moisture ingress, water tree, partial discharge, electrical tree, overheating, thermomechanical stress, and intrinsic breakdown.
Accessories, including splice and termination, have a significant role in the cable system failure for both MV and HV cables. Failure statistics of MV and HV cables are widespread. As a rule of thumb, one can consider almost equal distribution between cable failure, joint failure, and termination failure, each 33%. The CIGRE TB 560 presents a review of the experience of failures in terminations and joints (rated at 60 kV and above), including failure modes, consequences, and corrective actions. Accessory failure was caused by factors such as moisture ingress, insulation degradation, and poor workmanship.
Some of the power utilities and industrial cable owners run the MV cable systems to failure without any testing or maintenance plan after the commissioning. Replacement of cables based on failure or purely on age-based have disadvantages such as lowering the power system reliability and increasing the cost of repair or premature replacement. Aside from Factory Acceptance Tests (FAT), commissioning tests or site acceptance tests (SAT) have become very popular for both MV and HV cables in the past 15 years.
IEEE ICC provides a family of guides for field testing and evaluation of shielded cables.
- IEEE 400- Guide for Field Testing and Evaluation of Shielded Cables
- IEEE 400.1- Guide for Field Testingof Laminated Dielectric Shielded Power Cable Systems with HVDC Voltage
- IEEE 400.2- Guide for Field Testing of Shielded Power Cable Systems Using VLF
- IEEE 400.3- Guide for Partial Discharge Testing of Shielded Power Cable Systems in a Field Environment
- IEEE 400.4- Damped AC Voltage Testing
- IEEE 400.5- DC Field Testing of Extruded Cable Systems
- IEEE 1234- Guide for Fault Locating on Shielded Power CablesDGA
DGA is one of the most efficient tests for oil-filled cable diagnostics. IEEE Std. 1406-1998 is an old guide for the use of DGA analysis of electric power cable systems. The updated version of this guide is in its final stages of publication by the corresponding ICC working group.
Low dissolved gas concentrations are observed in cables operating in a reasonable manner. On the other hand, elevated dissolved gas levels indicate electrical and/or thermal abnormalities in the cable. Similar to power transformers, for cables, C2H2 is the most important dissolved gas, and its value should be close to zero for normal operation. It is imperative that the fluid extracted during sampling represents the cable system as opposed to the fittings. Fluid sampling is to cover both the cable system and accessories (splices and terminations) alongside the pressurizing unit. The cable accessories (terminations and splices) are typically equipped with sampling ports.
Oil Leak Detection
Oil leaks can threaten the performance of fluid-filled cables and harm the environment. Typical causes of oil leaks are pipe/sheath lead corrosion, external dam-
age due to excavation, poor workmanship and laying techniques, DC and stray current, mechanical stress, vibration, and compression from road construction work.
Injecting dyes, radioactive material, tracer gases, odorants, acoustic emission, radar, infrared, and even dogs are classic methods to detect oil leaks. Perfluorocarbon tracer (PFT) technique is a relatively new method for finding leaks in oil-filled high voltage cables. This method is based on finding the locations at which the pressure drops continuously after the cable oil is frozen at multiple spots. It can aggravate the state of the jacket, causing water ingress and corrosion. CIGRE TB 652, “Guide for Operation of SCFF Cable Systems- 2016”, proposed three techniques pertaining to the leak detection of SCFF cables: freezing, hydraulic bridge technique, and PFT injection.
Withstand VLF-Tan Delta
In the past 15 years, very low frequency (VLF) voltage testing in the frequency range from 0.01 to 0.1 Hz has increasingly been used for Hi-Pot acceptance for MV extruded cables. At present, the maximum voltage of the available VLF (0.1 Hz) test set is 200 kV peak. Therefore, the present VLF testing is limited to lower voltage HV cables.
VLF has also been used to perform VLF Tan-Delta for service aged MV polymeric cables. Based on more than 16,000 km of cable testing, IEEE 400.2- 2013 was developed to provide a detailed guide to test and analyze the results. The main advantage of such a test is that a small reactive power is needed compared to 50/60 Hz Hi-Pot testing. This IEEE guide provides recommendations to evaluate VLF Tan-Delta for PE-based (XLPE, TRXLPE), EPR (black, pink, discharge resistance) and PILC MV cables. One of the practical challenges with this guide is that it does not provide a clear direction for the intervention of decision making. This guide offers three condition assessment categories: 1- “No Action Required”, 2- “Further Study Advised”, 3- “Action Required”, of which categories 2 and 3 do not offer a clear action outcome. The future revision of IEEE 400.2 may provide a better recommendation and possibly include more than three assessment categories to help the indus- try for better cable fleet management.
Partial Discharge Tests
In the past 15 years, most of AC Hi-Pot commissioning has been conducted in conjunction with PD measurement. The onsite PD test is more popular for HV and EHV cables. However, some of the utilities have been doing PD testing for newly installed MV cables or service aged MV cables. IEEE 400.3- 2007, which provides a guide for onsite PD testing of shielded power cables, is under revision. It is expected that the revised IEEE 400.3 document will include the requirement of PD extinction voltage (PDEV) for different cable voltage classes and cable accessories.
One of the challenges of onsite PD measurement is that most of the existing guides refer to the conventional IEC 60270 method which assumes a lumped capacitance test object. This works well in the factory where the cable reel is lump. For cables with a length of a few kilometers or more, this is not a correct assumption. Background noise is also another challenge. For these reasons, unconventional onsite PD measurement is common, which allows a wideband PD measurement with a higher center frequency (1 MHz or higher). In order to reduce the effect of attenuation for long cables with multiple joints, it is common to perform a distributed PD measurement to monitor all the accessories. In such a setup, unconventional PD sensors such as HFCT, sheath sensor, differential field sensor, ultrasonic probe, or TEV can be used.
Over the last 15 years, as PD measuring instruments have become more sophisticated with the application of digital technology to reduce external noise and improve high-frequency electronics, many utilities, consultants, and testing service companies have added PD monitoring to the Hi-Pot test.
There are several HV power supplies that can be used for (monitored) withstand and PD testing, including 50/60 Hz power frequency, variable frequency resonance, VLF, and damped AC voltage.
Power Frequency or Near Power Frequency PD
This test requires a variable reactor or variable frequency convertor to create a resonance circuit with the cable capacitance. Such a setup can build a power frequency or a frequency in the range of 20 Hz to 300 Hz depending on the cable capacitance. CIGRE TB 728-2018, provides the latest international guide for the onsite withstand and partial discharge assessment of HV and EHV cable systems. According to this CIGRE guide, commissioning tests with PD monitoring should be carried out at 2 U0 for voltage ratings between 69 kV and 115 kV, 1.7 U0 for all voltage ratings between 132 kV and 400 kV, and 1.5 U0 for 500 kV rated and that there should be no detectable PD at 1.5 U0.
IEEE 400 has an active working group: “Constant Voltage AC Testing of Cable Systems (Resonant Testing)” to develop a guide for MV and HV cable onsite withstand testing with power frequency or near power frequency resonance circuit. This guide is expected to be published in 2021-2022.
A recent study commissioned by CIGRE, WG D1.48 found that the risk of space charge accumulation is very low, and the electric field distribution of VLF is similar to that at power frequency. However, the rate of electric treeing at VLF voltage is lower than power frequency primarily due to the lower number of partial discharges per time unit and reduced voltage drop across voids and electrical tree channels. On the other hand, using cosine rectangular VLF, it is possible to perform PD testing during the period of polarity reversal. The PD parameters, such as partial discharge inception voltage (PDIV) and PD magnitudes measured during the period of polarity reversal, are expected to be comparable to that at power frequency.
Damped AC PD
The Damped AC (DAC) test set uses high voltage DC to charge up the cable circuit under test to a specified voltage. Once this voltage is reached, the cable is discharged into an inductor to set up a
decaying high voltage oscillatory waveform on the cable circuit (20 Hz to 500 Hz). IEEE Std. 400.4-2015, specifies the magnitude of the charging voltage for each rated voltage, up to 230 kV. The number of shots at each voltage level is 50, and the test levels for new cable systems (peak voltage to ground) vary between 2 U0 and 3 U0. An advantage of using the DAC test is that both the PD inception and extinction voltages (PDIV/ PDEV) can be measured during any shot if PD exist.
DAC AC withstand and PD test is more popular in Europe than North America. There is limited data available comparing the PD characteristics (magnitudes, inception, extinction, etc.) between the power frequency and DAC tests.
Time Domain Reflectometry (TDR)
TDR can characterize changes in the cable impedance caused by splice, faults such as open or short, and deteriorated metallic shield. There are no unified success criteria for TDR testing. Another difficulty with TDR test is that there should be a balance between the injected pulse “amplitude resolution” and “time resolution”. TDR looks like a straightforward test; however, proper interpretation of the TDR test data requires the skill of the operator.
TDR can be used to assess the metallic shield. Cable shield corrosion, splice shield crimp corrosion, or splice thermal defects can change the resistance or the TDR waveform reflection. IEEE Std. 1617-2007 is a technical guide for condition assessment of the metallic shield. It provides corrosion categories of concentric neutral wires. This standard provides a four-level neutral corrosion condition based on the TDR pulse compared with the cable splice reflection. This guide is currently under revision by IEEE ICC.
NEETRAC Cable Diagnostic Focused Initiative-2016 – Chapter 11 is also a reliable practical guide for metallic shield assessment. CIGRE WG B1.55, “Recommendations for additional testing for submarine cables from 6 kV up to 60 kV”. recommends adding extra commissioning tests of TDR, OTDR, and sheath insulation resistance to SAT.
Dielectric spectroscopy including Frequency domain spectroscopy (FDS) or time-domain spectroscopy (TDS) has been used for more than 3 decades for diagnostics of MV and HV cables, especially PILC cables. For oil-filled cables, there is a direct relation between the paper insulation moisture percentage and FDS curve behavior. The preferred method for measuring the moisture in cellulose is FDS. FDS/TDS test technique has also been applied to polymeric cables. Unlike oil-filled equipment that do not require high voltage, polymeric cables require high voltage variable frequency source that can generate output voltage equal or higher than the cable rated voltage in a wide frequency range (0.001 Hz to 100 Hz). This is a practical challenge as the reactive power required for generating high voltage at 10 Hz to 100 Hz is high.
FDS can indicate the extent of the water treeing effect in XLPE cables and moisture ingress in oil-filled cables. Some recent studies show promising results to employ FDS for thermal aging of XLPE cables at voltages equal to or lower than the rated voltage. There is a newly published IEEE guide C57.161-2018 for power transformers diagnostics. There is no IEEE or IEC guide for FDS testing of underground cables. It is likely that IEEE ICC develops a guide for cable DS testing in the future.
Recovery Voltage Measurement (RVM)
RVM is a method where the cable circuit is charged using a DC voltage for a given time. This concept is based on applying DC voltage until a short circuit condition is produced and measuring the open-circuit voltage. The circuit is usually charged for 15 minutes, with voltages ranging from 1 to 2 kV. The charged circuit then discharges through a ground resistor within a short period of time. The open-circuit voltage is recorded versus time during the test.
The RVM test was introduced in the 1990s for power transformer testing and gained some popularity in the 2000s but experienced a decline in the 2010s. Limited experiments show that the RVM can be used for oil-filled cables. NEETRAC Cable Diagnostic Focused Initiative (2016) introduced a diagnostic factor D which is the ratio of recovery voltage at 2 U0 over U0. Clearly, this does not work for service aged polymeric cables as applying HVDC to XLPE cables over a suggested period of 15 min can introduce trapped charge and accelerate the cable aging.
Polarization/Depolarization Current (PDC)
PDC involves applying a DC voltage intherangeof100Vto5kVforaperiod of 5 to 30 minutes and discharge the cable in a few seconds through a resistor. The depolarization current is recorded. PDC identifies conduction and polarization effects in the insulation of the cable. An increase in the absorption current happens due to various effects inclusive of interfacial polarization and the presence of by-products due to PD, oxidation, and thermal degradation. On the other hand, the formation of voids in extruded cables can cause a reduction in the absorption current. Since the current measurement is in the range of nano or even pico ampere, reproducibility and overcoming noise are issues for onsite measurement. The interpretation of the results could be complicated. This technique may be sensitive to water trees. However, more onsite testing and validation is needed to accept this technique for practical diagnostics.
Metallic Shield Testing
Practically, I found the metallic shield integrity is one of the major causes of MV cables loss of life. The end-users and testing companies do not usually take this seriously. The industry focus is the insulation diagnostics by PD or VLF-Tan Delta. At the same time, it is essential to ensure concentric neutral integrity, especially for old and longer cables. Jacket integrity test, DC resistance of the shield, and TDR for corrosion investigation are the most important tests related to the metallic shield.
During the SAT commissioning, it is possible to measure the resistance of both the main conductor and the metallic shield (including the splice). However, it is a challenge to measure the metallic shield of a service aged cable unless one side of the grounded shield crimp is open or disconnected from the ground. There are test devices such as Ohm-Check that can be used to do an online neutral resistance measurement.
Broadband Impedance Spectroscopy
Cable impedance spectroscopy, often called line resonance analysis (LIRA) is based on frequency domain reflectometry. A very low voltage (3V to 5V) is applied to a cable system over a range of frequencies up to hundreds of MHz. The complex impedance of the cable is measured and the amplitude and phase at different resonance frequencies are measured. The analogy for this test is the power transformers SFRA test.
Based on the manufacturer’s claim, LIRA has greater advantages over TDR, including less influenced by noise, therefore more sensitive and accurate, greater possibility to focus on blind zone spots at the near end and measure on long cables, and global aging assessment. Theoretically, this technique can be applied to all LV, MV, and HV cables. LIRA is relatively new and needs additional work to verify its associated claims, e.g., in terms of the ability to detect oxidation, moisture ingress, and the influence of external noise, especially for long cables with such a very low voltage (3V to 5V).
In summary, there are various advanced cable test techniques available for the diagnostics of MV and HV cables. The most popular test based on industry practice is withstand Hi-Pot and PD for commissioning test and VLF Tan-Delta for maintenance test. The interpretation of advanced cable test diagnostics is a crucial component that determines the relative success of the testing and maintenance program. It is a common practice to engage a third party with field experience to perform advanced diagnostics and subsequent interpretation. There are several challenges and open issues specific to each advanced cable test diagnostic that remain to be addressed in the industry, such as:
• Onsite PD testing, including criteria of PDEV for different MV and HV cables, PD sensitivity, background noise, measurement frequency, proper calibration, signal attenuation, and PRPD interpretation. The revised IEEE 400.3 is expected to cover some of the concerns.
• Lack of field data and test equipment for HV transmission class cables using VLF Hi-Pot and PD and VLF Tan-Delta testing.
• Lack of available guidelines for FDS, RVM, and PDC.
Thus, diagnostics of underground cable is still in high demand and requires innovative ideas to improve the existing techniques, bring new ideas, and help the industry for a better condition assessment.
Research organizations and industry will have to cooperate more efficiently to improve the existing diagnostic techniques and offer new technologies toward a better practice and extending the life of the aged population of the cable fleet.
From The Editors
From the Editors’ Desk September-October 2020
This issue of the Magazine presents articles related to cable diagnostics and technology. Two of them, written by authors from Canada and Australia, summarize experiences and research activities on the use of dielectric response spectroscopy for diagnoses of insulation condition in medium voltage cables. The third article presents work performed in the USA on development of superconducting gas insulated cable system for power transmission at voltage level above 10 kV. Finally, the fourth article, from Norway, raises the importance of mesoscale material effect on the performance of cable joints.
The first article is entitled “Medium voltage XLPE cable condition assessment using frequency domain spectroscopy”. It is written by a team of authors from Canada. These are Ali Naderian Jahromi, Pranav Pattabi and Laurent Lamarre of METSCO Energy Solutions and John Densley of ArborLec Solutions. It provides a guide to the industrial users on how to utilize wide-range frequency domain dielectric spectroscopy (FDS) for the condition assessment of medium voltage cables. As an advancement over the VLF tan-delta testing, FDS offers deeper diagnostic insight by measuring the dielectric loss over a wide frequency range. The key diagnostics include aging due to thermal, water treeing effects and the influence of accessories. The FDS test results can be applied towards analyzing the insulation quality, extent of aging, electrical properties and in determining any changes to the structure of the dielectric system. The article also describes a zone-based categorization of aging effects in MV XLPE cables, developed over a wide frequency range (1 mHz to 1000 Hz). To advance the relevant criteria for assessing MV XLPE cables, a comprehensive analysis is performed based on established literature. A visual and practical guideline is presented to delineate the correlation of sample FDS test measurements with the corresponding aging effect and the frequency range of interest. Testing at lower frequencies (10 mHz to 0.1 Hz) is beneficial for evaluating the condition of MV XLPE cables (both new and service-aged). Since most of the commercially available VLF test equipment covers the 10 mHz to 0.1 Hz frequency range, it is recommended to measure the dielectric response of MV XLPE cables at least in this frequency range, especially for critical cable circuits.
The second article in this issue presents research results on “Dielectric response measurement of service-aged XLPE cables: From very low frequency to power frequency”. It is authored by Sayidul Morsalin and Toan Phung from the University of New South Wales in Sydney, Australia. This article presents an experimental study of tan-delta measurements from very low frequency (1 mHz) to power frequency (50 Hz) at various ambient temperatures (293 K-338 K) on short sections of service-aged 11-kV XLPE cable. The authors discuss physical and measurement (guarding) constraints when performing dielectric response tests in short pieces of XLPE insulated cables. Relaxation behavior under different ambient temperatures is analyzed. With increasing temperature, the tan-delta peak frequency of the tested cable specimens shifts to the higher frequency and the derived, on this basis, mean relaxation time enables calculation of the activation energy for different samples via Arrhenius equation. Frohlich’s analysis is also applied to investigate the distribution of dissipation factors under room temperature condition. It shows that the increasing relaxation time has influential roles on widening of the tan-delta graphs. Time domain measurements of polarisation/depolarisation currents are also reported, indicating an increase of insulation DC conductivity at elevated temperatures.
The third article reports on the research work aiming to develop “Novel gases as electrical insulation and a new design for gas-cooled superconducting power cables” and is authored by Taylor Stamm, Peter Cheetham, Chanyeop Park, Chul Han Kim, Lukas Graber and Sastry Pamidi, a joint team of researchers from Center for Advanced Power Systems, Tallahassee (FL), FAMU-FSU College of Engineering, Tallahassee, (FL), Mississippi State University (MS) and Georgia Institute of Technology (GA) in the USA. As for electric transport applications, liquid nitrogen has asphyxiation concerns due to its expansion ratio and comparable density to air in the event of a leak in a confined space; helium gas is considered a potential cryogen due to its lower expansion ratio, lower density than air and a wider operating temperature range. The wider operating temperature range of helium gas can thus be utilized to increase the current rating of high temperature superconducting (HTS) power cables, while also enabling system level optimization of the cryogenic cooling system. The low dielectric strength of helium gas is, however, limiting helium gas cooled HTS power cables to low voltage applications. This article presents an analysis on the dielectric strength of various helium based cryogenic gases. Modeling of these cryogenic gas mixtures is performed to find one with dielectric strength equivalent to liquid nitrogen. Measurements are shown using the mixture as part of the insulation for lapped-tape cables. As this configuration only shows limited improvements in dielectric behavior due to the occurrence of partial discharge at voltages below 10 kV, a superconducting gas insulated transmission line (S-GIL) concept is conceived and its model cables are designed for enhanced dielectric strength and potential use for electric transportation applications that can operate at voltages above 10 kV.
The fourth article of the issue is entitled “Considerations on the impact of material mesostructure on charge injection at cable interfaces”. It is authored by Espen Doedens and Markus Jarvid from Submarine and Land Systems (SLS) of Nexans in Halden, Norway. The authors discuss the impact of local structural features of interfaces and the bulk of polymeric material insulation, which despite several decades of industrial use, are still far from being well understood. The advancement of research in this area has progressed well during the recent years on the macroscopic scale and at atomic/ molecular level. However, many orders of magnitude in size difference between these two extremes still create difficulties in predicting effects that are governed by material mesostructure. To elucidate the latter, the article summarizes relevant work by mainly focusing on interfacial phenomena. One of them is surface roughness, well described in the mesoscopic range. Other interfacial effects strongly related to it, such as for example charge injection process and the impact of surface states happen at the atomic scale. It is, therefore, of great importance for ensuring a proper design methodology of cable accessories to understand how these different interfacial scale effects harmonize with each other.
News from Japan
Design of Analog Multipliers with Operational Amplifiers
Taylor & Francis Group
6000 Broken Sound Parkway – NW, Suite 300
Boca Raton, FL 33487-2742
182p. $129.95 (Hardcover), 2020
Operational amplifiers, generally referred to as op-amps, are very versatile electronic components. They are typically used as amplifiers, however, depending on their configuration, they can be used to create many different types of circuits that can be used to perform various functions.
The author has created a collection of various op-amp multiplier circuits classified in six basic categories – integrator, comparator, switch, low pass filter, peak detector, and sample and hold circuits. The book begins by describing the operation of each of these basic types. This includes schematics and fundamental equations describing the operation for each type. For example, equations for the output voltage are given for a low pass filter circuit to illustrate how the circuit produces a cut-off frequency.
The book then delves deeper into each of the six building blocks to illustrate how to build circuits that perform complex multiplier functions. These begin with conventional multipliers (log-antilog, transconductance, Gilbert, and wave multipliers) and continue with time division multiplexers, peak responding multiplexers, pulse position multiplexers both with and without voltage to period and voltage to frequency conversion.
If you are in need of these types of circuits then this book can provide you with some interesting topologies for various analog waveform multipliers. Electrical engineers, especially analog designers in need of circuit ideas could use this as a cookbook for selecting desired circuits.
Distributed Fiber Optic Sensing and Dynamic Rating of Power Cables
S. Cherukupalli and G. J. Anders
445 Hoes Lane
Piscataway, NJ 08854
John Wiley & Sons, Inc.
111 River Street
Hoboken, NJ 07030
235p. $135 (Hardcover), 2020
Besides being a conduit for light transmission, fiber optic (FO) cables have interesting properties that can be used to measure temperature, electric fields, electric current, medical applications, and even strain in materials. By distributing fiber optic cables throughout a structure or device, the desired property of the structure can be monitored. For example, fibers have been embedded in concrete structures to monitor distributed strain in large concrete structures such as dams. Another example for monitoring load and displacement changes is in underground mines, where an unexpected shift in the earth could be catastrophic.
Generally, due to the high cost of these systems, distributed fiber optic-based sensing systems are used in critical applications where failures would be devastating or very expensive to repair, or very difficult to access. One application gaining interest in the power industry is in monitoring distributed temperature in power transmission lines located in inaccessible areas (e.g. underwater, mountainous regions) or critical applications with growing power demands (e.g. high-density urban areas, data centers, financial, hospitals). FO cables are embedded in transmission lines to monitor the distributed temperature along these lines in order to maximize the thermal efficiency of the line. Today, large margins are used to insure adequate safety for transmission lines due to unplanned load demand and ambient temperature swings along the line, however, if the actual temperature of the line was known then the optimal loading of the line can be confidently performed by the utility and any overloading can be immediately be addressed.
This book provides a comprehensive review of distributed temperature sensing (DTS) measurement systems and fundamentals of FO temperature sensing, mainly for application in the electric power cable industry. FO cables, their construction, installation methods, and test methods are detailed with the main focus on application of DTS systems in the electric utility industry for power line temperature monitoring. Highlights include an explanation of cable ampacity rating calculations, FO cable placement in cables, and explanations on how the measured fiber temperature is used to determine the dynamic cable rating in real-time. DTS systems using the backscattering of laser pulses sent down a FO cable resulting in the wavelength shift of the Stokes, anti-Stokes, Raleigh, and Brillouin scattering signals to obtain temperature and strain information are explained.
Other features cover the design of FO cables and connectors and the testing methods. Communicating thermal information over SCADA and other methods is discussed along with calibration procedures for DTS systems and reviews of other possible applications such as fault location, vibration monitoring, and land and underwater cable monitoring.
Power cable engineers and manufacturers of power cables would be interested in this book. By gaining an understanding of the capabilities of potential application of DTS and FO sensing, the reader will gain new ideas and possibly create new opportunities by using this technology and at the very least gain a good understanding of FO based sensing systems.
Electric Drives, 3rd edition
I.O. Boldea and S.A. Nasar
Taylor & Francis Group
6000 Broken Sound Parkway – NW, Suite 300
Boca Raton, FL 33487-2742
671p. $132 (Hardcover), 2017
An electric drive is a system consisting of a motor and a power conversion unit. The use of a power conversion unit provides start, stop, protection and, in many cases, the ability to control motor speed. Oftentimes it is desired to vary the speed of a motor to better match the load being driven by the motor. Increasing efficiency and reducing stress on the system along with precise speed and torque control, gives an electric drive many advantages over a direct online (DOL) motor starter.
This book provides comprehensive coverage of the fundamentals of electric drives. It provides details on power electronic converters for drives and the application of these converters to various motor types including DC brush motors, induction motors, synchronous motors, large power drives, electric generator control, and the many practical issues with pulse width modulated (PWM) drives.
The many examples given, help illustrate methods and show how drives can be applied. The comprehensive background, along with MATLAB simulation files provided to help the reader quickly simulate drive models, and the latest information on machines for speed control, make this book an excellent resource for undergraduate or graduate course material on electrical machines and control. It can also serve as a reference for professionals working with electric drives who want to learn about the latest developments in electric drives or just need a comprehensive reference available.
Handbook on the Physics and Chemistry of Rare Earths, vol. 56
J.C.G Bunzli and V.K. Pecharsky
PO Box 211, 1000 AE Amsterdam
50 Hampshire Street
Cambridge, MA 02139
210p. $325 (Hardcover), 2019
The Handbook on the Physics and Chemistry of Rare Earths (including actinides) focuses on current topics in rare earth and actinide science. There are three chapters in this volume. The first chapter describes the role of rare-earth based units in quantum computing, the second focuses on the mechanisms of energy transfer in the sensitization of luminescent materials, and the third chapter covers uranium-containing superconducting materials.
Quantum computing is a key scientific development touching many different technologies including biology and medical fields. Information can be encoded into quantum bits (qubits) consisting of the superposition of two quantum states, analogous to digital 1 and 0’s. The advantage of quantum bits over traditional digital memory is that a quantum bit is much smaller in size for an equal size classical digital bit. The latest developments in quantum logic gates, which use rare earth elements to form gates, are described along with proof of concept and further challenges. Many references are presented which have to be used if you are new to this area of research since the authors assume an advanced reader.
Lanthanide luminescence is used in solid-state lighting, laser materials, optical amplifiers, wavelength converting materials for photovoltaic application and biomedical applications. This work concentrates on understanding the mechanisms of energy transfer from organic ligands to lanthanide ions to provide an update on recent theoretical developments and experimental methods for quantum yields and excited state lifetimes of luminescent materials.
The chapter on superconductors presents a lesser known aspect of superconductive materials, namely actinide-based superconductors. This work focuses on the chemical bonding of uranium-based superconductors in an effort to discover new higher temperature materials in this class of superconductors.
Material scientists working in any of these areas might be interested in this book. It presents highly theoretical work and requires a strong background in the topics being presented in order to follow the work being presented for some current topics in solid-state physics.
Explosive Ferroelectric Generators – From Physical Principles to Engineering
World Scientific Publishing Co.
5 Toh Tuck Link
27 Warren Street
Hackensack, NJ 07601
454p. $98 (Hardcover), 2019
Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization. The internal electric dipoles of a ferroelectric material are coupled to the material lattice so any mechanism that alters the material lattice will change the strength of the dipoles creating spontaneous polarization. The change in the spontaneous polarization results in a change in the surface charge which can cause current flow in the case of a ferroelectric capacitor even without the presence of an external voltage. Two stimuli that can change lattice dimensions of a material are force and temperature. The generation of a surface charge in response to the application of an external stress to a material is called piezoelectricity. A change in the spontaneous polarization of a material in response to a change in temperature is called pyroelectricity. By using high explosive charges, a compact multi-kilovolt multi-mega-amp pulse power generator can be created. An important ferroelectric material is lead zirconate titanate (PZT), which is part of the solid solution formed between ferroelectric lead titanate and anti-ferroelectric lead zirconate.
While ferroelectrics are probably more familiar in the low power range for applications such as sonar systems, ultrasound for medical imaging, and nano-position actuators, these applications generally produce hundreds of milliwatts of power. High pulse power applications generally require multi-megawatts of power.
While dating back to the 1950’s, ferroelectric explosive generators (FEG’s), have been recently improved over the last two decades and have gained renewed interested. These new ideas involve using ferroelectric materials, such as PZT for example, and a shock wave created from a small amount of high explosive material to produce a change in material polarization so strong that it produces a high-power pulse with 100’s KV and 100’s kA, similar to typical pulse power waveforms but in a very compact single-shot structure. Operating a ferroelectric material under these high mechanical stresses and high strain loading induces phase transitions and domain reorientation resulting in the generation of megawatt power for a brief period of time. However, the short time duration limits applications to those requiring high frequency such as resonant devices. One particular application is for gigawatt pulsed microwave generation.
This book introduces high-power, explosive driven, ferroelectric pulse generators, their principle of operation and applications. After an introduction to the subject matter, the author begins by examining the material properties of lead zirconate titanate ferroelectric ceramics. Next, shockwaves, created from high explosives, are described along with the physical principles of FEG’s. Designs of different types of FEG’s are shown including in-depth technical details of FEG’s using ceramics, single crystals, and ferroelectric films. Applications are also discussed.
This book would appeal to those who are interested in pulse power technology and pulse power generation. The fascinating ability to be able to achieve such incredible power levels with such compact devices is astonishing and could open up many new applications using the methods described in this well-written book, that is loaded with a wealth of experimental data, technical background on ferroelectric materials, high explosives, references, and many design ideas for making compact FEG’s.
Advances in Concentrating Solar Thermal Research and Technology
M. Blanco and L. R. Santigosa, Editors
Distributed by Elsevier
50 Hampshire Street
Cambridge, MA 02139
492p. $300 (Hardcover), 2017
Concentrating solar thermal (CST) energy in solar power plants is one way in which to use the sun’s thermal energy to liquify a solid material with a high thermal capacity and use this stored heat energy to create steam to turn a turbine to produce electricity. Large arrays of mirrors focused onto the solid, concentrating the sun’s energy to liquify a material such as sodium or other materials, is one way to use the sun’s vast energy to provide renewable energy and cutback on fossil fuel consumption. CST has also been used to refine and process minerals/metals and produces gases.
This book provides an introductory background on CST power plants as well as the latest advances in CST energy. It provides a deep understanding of the challenges of the various CST energy methods and describes the ongoing worldwide research to address these challenges.
It focuses on key CST plant components from mirrors and receivers to thermal storage and advanced control strategies and cost competitive concepts. Some of the topics cover new advances in solar absorber tubes, molten salts, and compressed gases to protect the molten salt from oxidation.
Control strategies are discussed with an emphasis on maximizing return on investment (ROI) based on the variability of sunlight. Other cost competitive plant concepts are also described including optimal heat transfer fluids at increased temperatures and solar power towers using supercritical CO2 and supercritical steam cycles and decoupled combined cycles. Thermal storage systems cover direct steam generation and thermochemical energy storage systems.
Rather than electricity production, CST can also be applied directly to a material processing plant to eliminate conversion inefficiencies by using the sun to directly melt materials rather than using electricity to heat the material. Material processing of commodity metal products and methods for H2 and CO production using solar energy are also covered.
Anyone wanting to learn about an alternative method for creating renewable energy storage other than photovoltaic and wind energy will find this book very interesting. It provides a very compelling case for using concentrated solar thermal for energy production and material processing using renewable resources. It has a sufficient introductory background to bring someone up-to-speed on this technology and with the latest technology also included, it will appeal to those already familiar with this technology but who want to learn more about the latest developments.
Blackbody Radiation – A History of Thermal Radiation Computational Aids and Numerical Methods
S.M. Stewart and R.B Johnson
Taylor & Francis Group
6000 Broken Sound Parkway – NW, Suite 300
Boca Raton, FL 33487-2742
412p. $215 (Hardcover), 2017
Optics plays an important role in many modern-day applications and more specifically, the behavior of blackbody radiation in many applications involving thermal and infrared systems, pyrometry, astrometry, meteorology, and illumination. Planck’s equation together with other related equations are the basis for all blackbody radiation studies performed today. This book focuses on both historical and modern computational methods used to evaluate Plank’s equation and various other associated equations. It also provides a background for understanding relevant optical radiation equations and concepts.
The book contains three sections. Section I introduces thermal radiation and the blackbody concept. It provides an interesting history of theoretical and experimental advancements in blackbody radiation with much of the book covered in the other two sections.
Section II explains Plank’s equation and the methods used to integrate the equation over finite limits including any nuances that can result depending on the conditions being evaluated. Some fundamental optical concepts such as inverse square law and numerical aperture are also presented which may be used when calculating blackbody radiation in optical systems. The book will greatly help the reader to understand the concept of blackbody radiation and how to solve associated equations which will aid in setting up and designing an optical system.
Section III provides a comprehensive review of both historical and modern computational methods for calculating blackbody radiation. Many of the historical optical radiation computational aids includes tables, nomograms, graphs, and slide rules, all rarely seen today! However, it is very interesting to see all these old-time methods presented together in one book and the methods used in the past, and still today, to calculate radiation problems. There is also some more recent computer-based methods presented for calculating these parameters but they are relatively limited.
Anyone interested in optical radiation history of blackbody radiation will find this book very interesting because of the comprehensive listing of historical computational aides presented and the obvious great depth of understanding conveyed by the authors in this book. Also, for those who calculate blackbody quantities it will be useful to learn about present and past methods. There is also a very extensive reference list at the end of the book for those looking for more details or in-depth coverage of specific topics in this area.