Acknowledgements: This Research was sponsored by ONR Funds: N Study on the Electrical Performance and Aging of Polymer Insulation S. Grzybowski High Voltage Laboratory Electrical and Computer Engineering Mississippi State University

Acknowledgements: This Research was sponsored by ONR Funds: N Research Projects Conducted for ESRDC l Accelerated Electrical Degradation of Motor Winding Insulation Energized by Distorted Voltage Waveforms l Electrical Degradation of High Voltage Power Cables Energized by Switching Impulses

Acknowledgements: This Research was sponsored by ONR Funds: N Study on Electrical Degradation of Solid Dielectrics Stresses that influence degradation –Applied Voltage Shape Magnitude Frequency –Environmental Condition Temperature Humidity Atmospheric Pressure Mechanical Pressure Surface Condition

Acknowledgements: This Research was sponsored by ONR Funds: N Accelerated Electrical Degradation of Motor Winding Insulation Energized by Distorted Voltage Waveforms Distribution Power System with Machine and AC/DC Converter AC/DC Converter will Generate Harmonics which Disturb the Voltage Waveform

Acknowledgements: This Research was sponsored by ONR Funds: N Arrhenius Exponential Inverse Power Models of Lifetime Evaluation Multi-Stress Model developed at MSU Electrical-Thermal

Acknowledgements: This Research was sponsored by ONR Funds: N Objective of the Study on Electrical Degradation of Machine Winding Insulation Previous studies outlined only the conditions experienced by these motors during the 60 Hz cycles of in-service stresses. There is a lack of information related to the lifetime of the insulation under high frequency pulses. The objective of the study is to gain new insights into the characterization of the electrical properties of ship motor winding insulation, stressed by distorted voltage waveforms (high frequency pulses) with respect to Power Frequency (60 Hz ac).

Acknowledgements: This Research was sponsored by ONR Funds: N Applied High Frequency Voltage Pulses D T V 

Acknowledgements: This Research was sponsored by ONR Funds: N Condition of Accelerated Electrical Degradation of Machine Winding Insulation Test parameters for the past two years study Twisted pair wire configuration –Polyester: MW35C (200°C rated), MW80C (155°C rated) Voltage level selected to avoid breakdown –1300 V, 40 kHz pulses, 50% duty cycle Temperature selected as 90% rated –180°C for MW35C and 140°C for MW80C Maximum Five samples for each test case –100, 500, 1000 hrs of accelerated degradation

Acknowledgements: This Research was sponsored by ONR Funds: N Condition of Accelerated Electrical Degradation of Machine Winding Insulation Test parameters for the current study Twisted pair wire configuration –Polyimide: MW16-C (240°C rated), –Polyamideimide MW81-C (220°C rated) Voltage level selected to avoid breakdown –1400 V, 20 kHz pulses, 50% duty cycle Temperature selected as 75% to 95% rated –From 180°C to 220°C for MW16-C, 165°C to 210°C for MW81-C Maximum Five samples for each test case –Samples will be aged until breakdown appears, Weibull analysis

Acknowledgements: This Research was sponsored by ONR Funds: N Evaluating Electrical Degradation of Machine Winding Insulation Evaluation for the past two years study Partial Discharge, Inception and Extinction Voltage –PDIV and PDEV at 60 Hz sinusoidal voltage after 500 hours of aging at specific condition Breakdown Voltage at 60 Hz Sinusoidal Voltage –After 500 hours of aging at specific condition Evaluation for the current study Partial Discharge at High Frequency Pulse Voltage –PD measured during the aging process at HF pulse voltage Time to Breakdown at High Frequency Pulse Voltage –At specific temperature and voltage

Acknowledgements: This Research was sponsored by ONR Funds: N Partial Discharge Measurement at 60 Hz ac Voltage For calibration Indicator ZmZm CoCo CKCK Tested sample

Acknowledgements: This Research was sponsored by ONR Funds: N Motivation to Measure PD at HF Square Pulse Voltage To perform partial discharge measurements in dielectrics and insulation for applied high frequency square pulse voltage. There are no commercially available devices that provide extended-time measurements (at Giga-sample per second) of partial discharge for applied high-speed, high voltage square pulses.

Acknowledgements: This Research was sponsored by ONR Funds: N Square Pulse Frequency Bandwidth For pulse voltage with a steep rise time such as 50 ns, the upper harmonics of the square pulse require ultra-wide band techniques for partial discharge measurements.

Acknowledgements: This Research was sponsored by ONR Funds: N Current Study Objectives for Partial Discharge Design Algorithm Development and Simulation Hardware Design and Construction User Interface Prototype Design and Implementation Signal Processing Controls Algorithms Artificial Samples Instrument Connections Artificial Samples Real Samples Simulation of Signal Processing Algorithms (De-noising, Classification, Quantification)‏ Measurement and Analysis

Acknowledgements: This Research was sponsored by ONR Funds: N Objective of the Study on Electrical Degradation of Power Cable Insulation Previous studies outlined only the conditions experienced by power cables during the 60 Hz cycles of in-service stresses and lightning impulses. There is a lack of information related to the electrical degradation and lifetime of the insulation under switching impulses. The objective of the study is to gain new insights into the characterization of the electrical properties of power cables, stressed by switching impulses.

Acknowledgements: This Research was sponsored by ONR Funds: N Electrical Degradation of High Voltage Power Cables Energized by Switching Impulses Power System with Distribution Cable Switching Impulses will be Generated During the Operation of Switch S 3

Cross-Section of 15 kV EPR and XLPE Power Cables PVC Jacket, T = 4.10 mm Copper Conductor Tape, T = 1.00 mm Semiconductor Layer, T = 2.40 mm EPR Insulation, T = 10.2 mm Semiconductor Sheath, T = 0.80 mm Copper Conductor Bundle, 19 Strands 14 AWG Wire, D = 10.0 mm PVC Jacket, T = 4.50 mm Copper Conductor Tape, T = 2.00 mm Semiconductor Layer, T = 1.80 mm XLPE Insulation, T = 11.8 mm Semiconductor Sheath, T = 0.40 mm Copper Conductor Bundle, 19 Strands 14 AWG Wire, D = 10.0 mm

Acknowledgements: This Research was sponsored by ONR Funds: N Evaluating Electrical Degradation of Cable Insulation Energized by 100 kV Switching Impulse 400 kV Impulse generatorStandard Switching Impulse, 250/2500 μs

Acknowledgements: This Research was sponsored by ONR Funds: N Sample Preparation for the Past Two Years Study The cable samples for testing were prepared as 3 m long segments. To eliminate the surface flashover when the switching impulses were applied to the cable and to measure the partial discharge properly, a shielding system was selected. A zinc-based semiconductive coating was applied on the outer surface of the cable, 15 cm in length. A 5 cm long layer of aluminum foil was located on surface of the semiconductive coating as a connecting point for testing and grounding. A 6 cm long layer of semiconductive tape with lower conductivity than the zinc-based coating was applied on each end of the zinc-based coating.

Acknowledgements: This Research was sponsored by ONR Funds: N Sample Preparation for the Current Study The cable samples for testing were prepared as 3 m long segments. PVC jacket, copper conductor tape were completely removed. Semiconductor layer (screen) of 30 cm was kept at the middle of the sample. A 6 cm long layer of aluminum foil was located on the surface of semi- conductive layer (screen) as a connecting point for grounding. Recent study indicated necessity of zinc-based semi-conductive coating is needed at the end of the semiconductor layer (screen) to eliminate surface partial discharges.

Acknowledgements: This Research was sponsored by ONR Funds: N Partial Discharge Characteristics for the Past Two Years Study Measurement of partial discharge apparent charge and pulse count for 15 kV EPR and XLPE cables, applied test voltage 8 kV ac

Acknowledgements: This Research was sponsored by ONR Funds: N Partial Discharge Characteristics for the Past Two Years Study Partial discharge inception voltage and extinction voltage for 15 kV EPR and XLPE cables versus applied switching impulses

Acknowledgements: This Research was sponsored by ONR Funds: N Partial Discharge Characteristics for the Current Study Measurement of Inception and Extinction voltage before using tapes Measurement of Inception and Extinction voltage after applying tapes

Acknowledgements: This Research was sponsored by ONR Funds: N Conclusions on Electrical Degradation of EPR and XLPE Power Cables Degradation of EPR and XLPE cables takes place as a result of applied switching impulses. The tested sample of XLPE has shown more signs of degradation than the sample of EPR. The ac breakdown voltage of the XLPE cable dropped significantly after 5000 applied impulses. For better understanding of the degradation phenomena, a larger number of switching impulses need to be applied to the cables.