Deeper Insight into the Relationship between Experimental Expressions of Conductivity and DC Electric field in cables

This paper aims at a deeper insight into analytical relationships between experimental expressions of electrical conductivity and electric field in DC cables. An analytical relationship was found in a previous paper focusing on one model of electrical conductivity only. Here the analysis is broadened to another more complex model used sometimes in the technicalscientific literature, and the derivation of the analytical relationship between the experimental conductivity expression and the electric field is carried out parametrically. A case study for DC-XLPE cable insulation is shown for the sake of illustration. The results agree with the literature values. While the temperature coefficient of conductivity a is weakly dependent on temperature, the stress coefficient of conductivity b is strongly dependent on electric field, especially for typical fields of HVDC cables

Issues in Space Charge Measurments with the PEA Technique in HVDC Cables: Applicative Case Study

This work is performed to assess the role played by some quantities affecting space charge measurements with the Pulse Electro-Acoustic (PEA) technique in HVDC power cables. In particular, the possible disturbances to the PEA signal arising when measuring space charges with a commercial PEA cell not optimized for the cable system to be measured, which may affect consequently the estimation of trapped charge and the field profile within the insulation, are analyzed. The results show that in particular, cable length, cell arrangement and exposed semicon length play a role and may affect the PEA signal significantly. Thus they have to be optimized for the cable to be measured

Pulsed Electro-Acoustic Method for specimens and cables employed in HVDC systems: Some feasibility considerations

Recent experiments on the use of the PEA method for testing dielectric materials in specimens and comparison with a detailed model provide an insight of the phenomenon and suggest the need of adopting similar models also for cables. What is said is even more important considering the possible future adoption of the PEA methodology to test DC cables for Pre-Qualification and Type Tests. The use of an accurate model of the PEA cell used for testing specimens and related experiments prove that the thickness of the different parts composing the PEA setup is a basic element for providing accurate charge reading and interpretation of the phenomenon. Both simulation and experimental results, carried out for flat specimens, show the importance of the PEA cell components and sample features in the output charge profile. In this work, we demonstrate that these considerations for flat samples are also valid for cable specimens. This aspect, and the other critical issues encountered in the experimental test on a Full-Size cable, have been reported in this paper, as well as some possible solution

Axillary reverse mapping (ARM) in breast cancer and evaluation of ARM related nodes metastatic status

Objectives: ARM technique aims at preventing lymphedema in patients undergoing axillary lymph node dissection (ALND) by identifying and sparing nodes and lymphatic pathway draining upper limb. Aim of our study was to evaluate ARM method and metastatic status of ARM related nodes. Methods: Fifty breast cancer patients scheduled for ALND were enrolled in a prospective study on ARM radiotracer-based procedure. All patients underwent subcutaneous injection of Tc99m-colloid in both tumour ipsilateral and contralateral hand as control, mean activity per hand 97.7MBq (73-130) fractioned in all web spaces. Scintigraphic images were acquired on arms and axillae early (5-20') and late (2-3h) after injection in order to visualize the most active nodes (ARMn). ALND was performed using a gamma-probe for radioguided surgery in order to identify ARMn. ARMn histologic examination was performed separately from other ALND nodes. Results: Scintigraphy allowed detecting ARMn in both axillae in all patients: no change in ARMn visualization from early to late acquisitions was observed. Surgeons identified and removed 58 ARMn in 50 patients: 1 in 45 patients, 2 in 2, 3 in 3. Histology demonstrated the absence of metastatic involvement in ARMn in 48 patients (96%); metastasis was found in 2 cases (4%) of aggressive and extended disease, respectively (G3 pT1 pN2 ductal and pT2 pN3 lobular infiltrating carcinoma). Differently, ALND resulted positive for axillary metastatic involvement in 29/50 patients (58%) and negative in 21 (42%). Conclusions: In our study ARMn resulted free from disease in 96% of patients, being consistent with data published in Literature. ARM technique provided surgeons with a precise mapping of nodes that drain arm and could be preserved, differentiating them from breast draining ones to be removed in ALND: this could represent an important contribution in breast surgery potentially preventing lymphedema. A study to evaluate potential benefits of ARMn preservation is starting in our Institution

Wireless partial discharge tracking on cross-linked polyethylene MV and HV cables

none8noMedium voltage (MV)/high voltage (HV) cable lines are high-value assets and require substantial costs for their installation or replacement. For this reason, the capability to assess the condition of cable lengths and accessories on site is of great importance. Cross-linked polyethylene (XLPE) insulation is extensively used for MV, HV, and extra-high voltage (EHV) class cables [1] thanks to its excellent voltage-endurance and thermomechanical properties. In particular, XLPE-insulated cables feature substantially lower losses, easier manufacturing and jointing procedures, better environmental compatibility, and higher operating temperature compared with impregnated paper cables, which lead to lower costs in procurement and operation [2], [3].noneMadonia, Antonino; Sanseverino, Eleonora Riva; Romano, Pietro; Troia, Ivan; Bononi, Stefano Franchi; Albertini, Marco; Giannini, Simone; Mazzanti, GiovanniMadonia, Antonino; Sanseverino, Eleonora Riva; Romano, Pietro; Troia, Ivan; Bononi, Stefano Franchi; Albertini, Marco; Giannini, Simone; Mazzanti, Giovann

Feasibility of Space charge measurements on HVDC cable joints

The first time that the feasibility of space charge measurements on full sized HVDC cable joints has been explicitly considered and whether the PEA and TSM techniques could be utilized

Activation material selection for multiple foil activation detectors in JET TT campaign

In the preparation for the Deuterium-Tritium campaign, JET will operate with a tritium plasma. The T + T reaction consists of two notable channels: (1) T + T -> He-4 + 2n, (2) T + T -> He-5 + n -> He-4 + 2n. The reaction channel (1) is the reaction with the highest branching ratio and a continuum of neutron energies being produced. Reaction channel (2) produces a spectrum with a peak at 8.8 MeV. A particular problem is the ratio between the individual TT reaction channels, which is highly dependent on the energy of the reacting tritium ions. There are very few measurements on the TT spectrum and the study at JET would be interesting. The work is focused on the determination of the spectral characteristics in the TT plasma discharges, especially on the presence of the 8.8 MeV peak, a consequence of channel (2) of the TT reaction. The possibility to use an optimized set of activation materials in order to target the measurement of the 8.8 MeV peak is studied. The lower limit of detection for the channel (2) ratio within the TT reaction is estimated and the influence of DT source neutrons, which are a consequence of deuterium traces in the plasma, is investigated