High voltage capacitors designed to avoid catastrophic failure modes
A major concern in the operation of high voltage capacitors is the failure mode at end of life. While progress has been made in this area at lower voltages, little has changed for high current capacitors operating above 30 kV in steady state and pulsed power applications. Based on a new development at Maxwell Energy Products, Inc., it is now possible to build capacitors that can operate with a high degree of safety at high voltages. The capacitors reach the normal end of life, while avoiding the catastrophic failures, collateral damage, and unscheduled maintenance, associated with the normal failure mode of today's high voltage capacitors. This paper discusses the problem, capacitor failure modes, capacitor designs and describes a solution to the problem of catastrophic high voltage capacitor failures.
Influence factors for the self-healing of metallized polypropylene capacitors
After the local breakdown of the metallized film, the self-healing of the capacitor is influenced by several factors, including the capacitance of metallized capacitor, pressure, as well as the applied voltage. In this paper, they are investigated fundamentally in reference to their influence towards the insulation recovery of the metallized polypropylene. Single metallized polypropylene film and metallized film capacitors are used as experimental samples to study the effect of these factors after local breakdown of the film under the conditions of impregnation and nonimpregnation. The results show that, these factors impose their influences via the infusion energy passing the breakdown path. It is also found that excess the infusion energy will be adverse to the self-healing of metallized polypropylene capacitors.
Introduction and experience with the primary mail services based on their names for students
Kyushu University provided mail service based on student IDs such as "1AB10123X" to the university students for many years. Using this model, we had problems communicating with the students who graduated from the University and enrolled in the graduate school. The students received new mail addresses based on their new student IDs such as "2AB12789Y". Faculty members were forced to change the student mail addresses in the mailing lists and in their mail client address book. Furthermore, students were forced to notify the e-mail address change to all of their existing contacts. We introduced a new mail system to provide addresses based on the student name, as well as student ID in April 2011. The new naming convention uses the following format: lastname.firstname.999 where 999 is a random number of 3 digits. Students can select some combination patterns of their first and last names for Japanese. We also consider the middle names for foreign students. In the system implementation, we did not have the formal information of alphabetical names for students. We generated alphabetical names from Japanese Katakana names. It is not easy for us to get the appropriate name in this manner. We implemented a confirmation stage of the alphabetical name at first use, and then students can select their mail addresses for their convenience. We paid much attention to the user interface in the system. Since April 2011, the number of users who use the mail address based on their own name has been increasing gradually. This paper will detail the usage status of the new system.