@mastersthesis{MTMT:32812745, title = {Investigation of Aging Processes of Insulating Materials in Multi-Stress Environment: the Role of Thermo-Mechanical and Radio-Mechanical Stresses on Low-Voltage Nuclear Cables Insulation}, url = {https://m2.mtmt.hu/api/publication/32812745}, author = {Afia, Ramy Saad Abdelatty}, publisher = {Budapest University of Technology and Economics}, unique-id = {32812745}, year = {2022}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259} } @article{MTMT:32800790, title = {Implementation of Non-Destructive Condition Monitoring Techniques on Low-Voltage Nuclear Cables: II. Thermal Aging of EPR/CSPE Cables}, url = {https://m2.mtmt.hu/api/publication/32800790}, author = {Mustafa, Ehtasham and Afia, Ramy Saad Abdelatty and Nawaz, Aamir and Nouini, Oumaima and Tamus, Zoltán Ádám}, doi = {10.3390/en15093231}, journal-iso = {ENERGIES}, journal = {ENERGIES}, volume = {15}, unique-id = {32800790}, issn = {1996-1073}, abstract = {Determining the aging state of low-voltage nuclear power plant cables using a nondestructive and reliable condition monitoring technique is highly desirable as the cables experience multiple aging stresses during the service period. This paper deals with the implementation and investigation of such nondestructive techniques, which can detect the overall aging state of low-voltage instrumentation and control (I&C) cables, which are subjected to accelerated thermal aging. The dielectric spectroscopy, extended voltage response, and polarization–depolarization current as nondestructive electrical aging techniques were used for the investigation purpose, while the elongation at break was also adopted as a mechanical measurement and for comparison. Prominent variations in the electrical parameters for the insulation and jacket were observed, whereas the elongation at break for both materials also decreased under thermal aging. Based on the electrical techniques, aging markers were selected that showed a strong correlation with the aging and elongation at break, proving the ability of the adopted electrical methods as a nondestructive condition monitoring technique.}, year = {2022}, eissn = {1996-1073}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Nawaz, Aamir/0000-0002-1992-0945; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:32542220, title = {Aging Assessment of XLPE/CSPE LV Nuclear Power Cables Under Simultaneous Radiation–Mechanical Stresses}, url = {https://m2.mtmt.hu/api/publication/32542220}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, doi = {10.1016/j.egyr.2021.11.113}, journal-iso = {ENERGY REP}, journal = {ENERGY REPORTS}, volume = {8}, unique-id = {32542220}, issn = {2352-4847}, abstract = {The preliminary results of an ongoing laboratory cable aging program are reported in this article. This work deals with the effect of simultaneous radiation-mechanical aging on the electrical and mechanical properties of XLPE/CSPE low-voltage un-shielded nuclear power cables. The dielectric response, particularly the complex permittivity and the polarization/depolarization current (PDC), were investigated. At the same time, the Shore D hardness measurement was conducted as a mechanical property test. Cable samples were coincidingly aged under a bending diameter of 15 cm and a total dose of 240 kGy gamma-irradiation at a 0.5 kGy/h dose rate. The real and imaginary parts of permittivity were investigated over a frequency range from 200 mu Hz to 1 Hz. The electrical parameters presented a monotonic increase with aging. Besides, the cable hardness has increased with increasing the radiation dose. Furthermore, the insulation conductivity has risen with aging, which strongly correlates with the imaginary permittivity at 1 mHz. The obtained results showed an excessive degradation of the cable samples under the combined radiation-mechanical aging as the insulation electrical and mechanical properties showed a good agreement. (c) 2021 The Author(s). Published by Elsevier Ltd.}, year = {2022}, eissn = {2352-4847}, pages = {1028-1037}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:32542215, title = {Condition Monitoring of Photovoltaic Cables Based Cross-Linked Polyolefin Insulation Under Combined Accelerated Aging Stresses: Electrical and Mechanical Assessment}, url = {https://m2.mtmt.hu/api/publication/32542215}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, doi = {10.1016/j.egyr.2021.11.122}, journal-iso = {ENERGY REP}, journal = {ENERGY REPORTS}, volume = {8}, unique-id = {32542215}, issn = {2352-4847}, abstract = {The degradation of insulating materials has been recognized as a prime cause of the precocious failure of cable systems. In this research, the role of simultaneous thermal and mechanical stresses on the insulation integrity of cross-linked polyolefin insulation based low voltage photovoltaic cables was studied. The cable samples were subjected to combined thermal–mechanical aging at 120 °C for 120, 189, 258, 396, 636, 876, 1000, and 1120 h aging cycles. The effect of the accelerated aging tests on the insulation integrity of the cross-linked polyolefin was explored by electrical and mechanical techniques. The electrical assessment was based on the measurement of the complex permittivity with frequency variation between 100 mHz to 500 kHz and the measurement of the decay and return voltage slopes. The Shore D hardness as a mechanical testing technique has been carried out. Surprisingly, after 1120 aging hours, the real part of permittivity was almost the same as the pristine case. Also, the imaginary part of permittivity retarded below the pristine case. That was more dominant at frequencies higher than 10 Hz. A good agreement was found between the decay voltage slope and the imaginary permittivity at 1 Hz. Also, between the return voltage slope and the real permittivity. The cable hardness showed anomalous behavior with aging. This shows the ability of the cross-linked polyolefin to recover its mechanical properties when subjected to elevated temperature.}, year = {2022}, eissn = {2352-4847}, pages = {1038-1049}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @inproceedings{MTMT:32592782, title = {Thermal-Mechanical Accelerated Aging Tests of XLPO Insulation Based Photovoltaic Cables: Inverse Aging Behavior}, url = {https://m2.mtmt.hu/api/publication/32592782}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, booktitle = {2021 IEEE 4rd International Conference and Workshop in Óbuda on Electrical and Power Engineering (CANDO-EPE)}, doi = {10.1109/CANDO-EPE54223.2021.9667894}, unique-id = {32592782}, abstract = {The output power of photovoltaic (PV) systems relies greatly on their DC cable systems as these cables provide the link between the main PV systems components, solar modules, inverters, batteries, and charge controllers. These cable systems are exposed to harsh operating conditions such as ultraviolet radiation, thermal, electrical, and mechanical stresses. Thus, the cables’ insulation degrades, and their functionality is not assured. In this research, samples of DC PV cables have been exposed to combined simultaneous thermal and mechanical stresses for 258, 396, 636, 876, 1000, and 1120 hours. While the cable samples were placed in an air circulating oven at 120 °C, they have been bent on a mandrel of 6 cm diameter. The impact of the thermal-mechanical aging stresses on the cables’ insulation integrity has been explored by implementing the dielectric spectroscopy technique and the Shore D hardness measurement. The real and imaginary parts of permittivity presented a non-monotonic behavior with aging. Besides, the Shore D hardness increased after 396, and 636 aging hours. In contrast, it decreased after the subsequent aging cycles, 876, 1000, and 1120 hours. The obtained results suggest that the XLPO could recover its mechanical properties while being exposed to an elevated temperature for an extended period.}, year = {2021}, pages = {31-36}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:32535798, title = {Comparison of Mechanical and Low-Frequency Dielectric Properties of Thermally and Thermo-Mechanically Aged Low Voltage CSPE/XLPE Nuclear Power Plant Cables}, url = {https://m2.mtmt.hu/api/publication/32535798}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, doi = {10.3390/electronics10222728}, journal = {ELECTRONICS (SWITZ)}, volume = {10}, unique-id = {32535798}, abstract = {During the service period of low-voltage nuclear cables, multiple stresses influence the aging of polymeric materials of cables. Thermal and radiation stresses are considered service aging factors in qualification tests, while the standards usually do not prescribe mechanical stress. CSPE/XLPE insulated nuclear cable samples were exposed to thermal and combined thermo-mechanical aging for more than 1200 h at 120 & DEG;C. The real and imaginary parts of permittivity were measured in the 200 mu Hz to 50 mHz range as dielectric properties. The Shore D hardness of the samples was measured to analyze the mechanical characteristics of the cable. To characterize the dielectric spectrum, derived quantities, namely central real and imaginary permittivities and real and imaginary permittivities' central frequencies were calculated. The change of dielectric spectra did not show a clear trend with aging, but the imaginary permittivity's central frequency was higher by 0.5 mHz in the case of thermo-mechanically aged samples. The Shore D hardness was also higher on the thermo-mechanically aged samples. These findings show the combined aging has a higher impact on the insulation properties. Hence, involving the mechanical stress in the aging procedure of cable qualification enables the design of more robust cables in a harsh environment.}, keywords = {hardness; Nuclear power plant; Dielectric Spectroscopy; thermal degradation; POLYMER DEGRADATION; low-voltage cables; thermal-mechanical aging}, year = {2021}, eissn = {2079-9292}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:32185759, title = {Aging Mechanisms and Non-Destructive Aging Indicators of XLPE/CSPE Unshielded LV Nuclear Power Cables Subjected to Simultaneous Radiation-Mechanical Aging}, url = {https://m2.mtmt.hu/api/publication/32185759}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, doi = {10.3390/polym13183033}, journal-iso = {POLYMERS-BASEL}, journal = {POLYMERS}, volume = {13}, unique-id = {32185759}, abstract = {Low-voltage cable systems in nuclear power plants are key components that have a crucial role in the safe operation of nuclear facilities. Thus, the aging management of cable systems is of utmost importance as they cannot easily or economically be replaced or upgraded. Therefore, there is a continuous need to develop reliable non-destructive condition monitoring techniques, mostly based on the measurement of the dielectric properties of cable insulation. This paper introduces the changing of dielectric and mechanical properties of XLPE insulated and CSPE jacketed unshielded low-voltage nuclear power plant power cable in case of simultaneous mechanical and radiation aging. The cable samples were bent and exposed to 400 kGy gamma irradiation with a 0.5 kGy/hr dose rate. Dielectric response (real and imaginary permittivity) in the 0.1 Hz−1 kHz frequency range, extended voltage response (EVR), and the Shore D hardness test techniques were measured to track aging. The electrical and mechanical parameters have increased monotonically with aging, except the imaginary permittivity, which increased only at frequencies higher than 10 Hz. Furthermore, different quantities were deducted based on the frequency and permittivity data. The electrical parameters and deducted quantities correlation with aging and mechanical parameters were investigated. Since the deducted quantities and the electrical parameters are strongly correlated with absorbed dose and mechanical properties, the electrical measurements can be applied as a non-destructive aging indicator for XLPE/CSPE unshielded low-voltage nuclear power cables.}, year = {2021}, eissn = {2073-4360}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:32152429, title = {Implementation of Non-Destructive Electrical Condition Monitoring Techniques on Low-Voltage Nuclear Cables: I. Irradiation Aging of EPR/CSPE Cables}, url = {https://m2.mtmt.hu/api/publication/32152429}, author = {Mustafa, Ehtasham and Afia, Ramy Saad Abdelatty and Nouini, Oumaima and Tamus, Zoltán Ádám}, doi = {10.3390/en14165139}, journal-iso = {ENERGIES}, journal = {ENERGIES}, volume = {14}, unique-id = {32152429}, issn = {1996-1073}, year = {2021}, eissn = {1996-1073}, pages = {5139}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:31987835, title = {Parameterization of Debye Model for Dielectrics Using Voltage Response Measurements and a Benchmark Problem}, url = {https://m2.mtmt.hu/api/publication/31987835}, author = {Mustafa, Ehtasham and Németh, Regina Mária and Afia, Ramy Saad Abdelatty and Tamus, Zoltán Ádám}, doi = {10.3311/PPee.16399}, journal-iso = {PERIOD POLYTECH ELECTR ENG COMP SCI}, journal = {PERIODICA POLYTECHNICA-ELECTRICAL ENGINEERING AND COMPUTER SCIENCE}, volume = {65}, unique-id = {31987835}, issn = {2064-5260}, year = {2021}, eissn = {2064-5279}, pages = {138-145}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} } @article{MTMT:31803167, title = {Electrical and Mechanical Condition Assessment of Low Voltage Unshielded Nuclear Power Cables Under Simultaneous Thermal and Mechanical Stresses: Application of Non-Destructive Test Techniques}, url = {https://m2.mtmt.hu/api/publication/31803167}, author = {Afia, Ramy Saad Abdelatty and Mustafa, Ehtasham and Tamus, Zoltán Ádám}, doi = {10.1109/ACCESS.2020.3048189}, journal-iso = {IEEE ACCESS}, journal = {IEEE ACCESS}, volume = {9}, unique-id = {31803167}, issn = {2169-3536}, year = {2021}, eissn = {2169-3536}, pages = {4531-4541}, orcid-numbers = {Afia, Ramy Saad Abdelatty/0000-0002-2455-1259; Tamus, Zoltán Ádám/0000-0002-0092-7565} }