The Insulation of HVDC Extruded Cable System Joints. Part 1: Review of Materials, Design and Testing Procedures

This position paper by the DEIS HVDC Cable Systems Technical Committee provides a review of existing diagnostic electrical and dielectric techniques for testing the insulation of polymeric extruded HVDC cable joints in the present Part 1. Here, the state of the art on the insulation of HVDC extruded cable system joints is covered with reference to types, design and testing techniques. This helps to identify routine tests as the first target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers' practices for quality control of the insulation of accessories during routine tests and VHF/UHF wireless sensors as the best tool for performing such measurements on joints in the noisy factory environment. Thereby, a novel protocol for the measurement of partial discharges using AC voltages and VHF/UHF sensors, for quality control during routine tests on such joints, is derived in the next Part 2. This protocol is the main novelty of this investigation

The Insulation of HVDC Extruded Cable System Joints. Part 2: Proposal of a New AC Voltage PD Measurement Protocol for Quality Control during Routine Tests

The review of materials, design and testing of joints for HVDC extruded cable systems provided in previous Part 1 paved the way to this Part 2 position paper by the DEIS HVDC Cable Systems Technical Committee, whose aim is to remedy the scarcity of existing standardized tests on joints. After a sound analysis, here routine tests are identified as the first practical target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers’ experience for quality control of joints during routine tests and VHF/UHF wireless sensors as the best tool for such measurements in the noisy environment of factories. Thereby, a novel protocol for PD measurement using AC voltages and VHF/UHF electromagnetic sensors, for quality control during routine tests on HVDC extruded joints, is proposed

Feasibility of Space Charge Measurements on HVDC Cable Joints

This review article aims at illustrating the starting of the activities carried out by the Study Group from the viewpoint of the assessment of the state of the art in the measurement of SC in HVDC extruded cable system joints

2019 EACTS Expert Consensus on long-term mechanical circulatory support

Long-term mechanical circulatory support (LT-MCS) is an important treatment modality for patients with severe heart failure. Different devices are available, and many-sometimes contradictory-observations regarding patient selection, surgical techniques, perioperative management and follow-up have been published. With the growing expertise in this field, the European Association for Cardio-Thoracic Surgery (EACTS) recognized a need for a structured multidisciplinary consensus about the approach to patients with LT-MCS. However, the evidence published so far is insufficient to allow for generation of meaningful guidelines complying with EACTS requirements. Instead, the EACTS presents an expert opinion in the LT-MCS field. This expert opinion addresses patient evaluation and preoperative optimization as well as management of cardiac and non-cardiac comorbidities. Further, extensive operative implantation techniques are summarized and evaluated by leading experts, depending on both patient characteristics and device selection. The faculty recognized that postoperative management is multidisciplinary and includes aspects of intensive care unit stay, rehabilitation, ambulatory care, myocardial recovery and end-of-life care and mirrored this fact in this paper. Additionally, the opinions of experts on diagnosis and management of adverse events including bleeding, cerebrovascular accidents and device malfunction are presented. In this expert consensus, the evidence for the complete management from patient selection to end-of-life care is carefully reviewed with the aim of guiding clinicians in optimizing management of patients considered for or supported by an LT-MCS device

Classification of partial discharges for DC equipment

Computer aided partial discharge detection, recognition and classification at AC voltage has become common practice in recent years. Characteristic discharge phase distributions have been found, thus providing the possibility to recognise and assess possible defects in HV apparatus. For diagnostic purposes, fingerprints from these distributions can be derived and compared to those previously ascertained and stored in a data-bank. For DC voltage a similar technique can be used when the phase angle is replaced by the time between discharges. Successful results have been obtained by employing this method on several artificial defect

Partial Discharge Diagnostic for DC Equipment

Partial discharges (PD) are widely used to assess the insulation quality of High Voltage (HV) constructions. For AC voltage, techniques for classification and recognition of single defects have been developed recently. This paper presente results of PD diagnostics at DC voltage on HV DC capacitors by using a method dedicated to DC voltage applications. Dominating effects in the capacitors could be recognized and the resulting PD patterns are explained in terms of physical processes

Influence of Manufacturing on Dielectric Performance of Nanocomposites

Nanodielectrics show remarkable dielectric properties like dielectric breakdown strength, or both surprisingly low and high values for the relative permittivity. These changes compared to materials filled with conventional, microscale filler are often attributed to the high surface area of nanoparticles and their aspect ratio. The even dispersion and distribution of particles in a polymer host is also very important for the dielectric performance of nanocomposites. The influence of the manufacturing and synthesis process on the other hand is often neglected or omitted. Even for the same combination of base materials, the resulting dielectric properties can vary to a great extent. This partly explains large differences encountered in literature regarding dielectric properties of nanocomposites. Focus of this paper is to illustrate the influence that the synthesis process has, not only on dispersion and distribution of particles, but also the structure of a polymer host like epoxy. Examples include nanocomposites based on bisphenol-A epoxy resin with different filler materials

The role of supply frequency in the evaluation of partial discharge inception voltage in XLPE-embedded cavities

We have investigated recently the role of voltage supply frequency on partial discharge inception voltage (PDIV) measurement for cavities embedded in a polyethylene matrix. From the experimental results, it was ascertained that lower frequencies could lead to lower PDIV values, whereas increasing the supply frequency could quench partial discharge activity. Some explanations were proposed, but a further experimental activity was planned to confirm (or reject) some of the hypotheses. In this paper, the results presented earlier are further validated through an extensive experimental survey. The conclusions derived from the present data are that PDIV does not change appreciably with frequency, whereas, its measured value does. Very low frequency systems seem to provide results that are more accurate than those obtained using higher frequencie