Title: Electrical Protection of Superconducting Magnet Systems

A preliminary comparison of several different coil protection and electrical connection schemes for large superconducting toroidal magnet systems (STMS) is carried out. The tentative recommendation is to rely on external dump resistors for coil protection and to connect the coils in the toroidal magnet in several parallel loops (e.g., every fourth coil is connected into a single series loop). For the fault condition when a single coil quenches, the quenched coil should be isolated from its loop by switching devices. The magnet, as a whole, should probably be discharged if more than a few coils have quenched.

This report includes the first two quarters study of available information on schemes for protecting superconducting magnets. These schemes can be divided into two different categories. The first category deals with the detection of faulty regions (or normal regions) in the magnet. The second category relates to the protection of the magnet when a fault is detected, and the derived signal which can be used to activate a safety system (or energy removal system). The general detection and protection methods are first described briefly and then followed by a survey of the protection systems used by different laboratories for variousmore » magnets. A survey of the cause of the magnet difficulties or failures is also included. A preliminary discussion of these protection schemes and the experimental development of this program is given.« less

This report describes the analysis tools developed at West Virginia University that can be implemented to optimally design coal mine electrical systems. The basic analytical tools for all power systems are the load-flow and short-circuit analysis. Well known programs have been developed for analysis of ac transmission and distribution systems, but they are not applicable to a system that has combined ac-dc distribution, such as a coal mine power system. Furthermore, the tipology of a coal mine electrical system changes continuously due to the movement of locomotives on the track. In first section of this report, algorithms for carrying outmore » load-flow and short circuit analysis of a coal mine electrical system are described. Results from the study of a typical coal mine system are presented. In the second section, a method is described to optimally size power cables for cyclic loads. This method is based on the development of a thermal-electric mode for a low-voltage power cable. Results from experimental verification of the model are also presented.« less

This report presents the results of an investigation into the feasibility of periodically measuring parameters of the insulation for a mine electrical power system to detect incipient faults. The variety of insulation parameters evaluated included insulation resistance, dissipation factor, power factor (versus applied voltage), current harmonics, leakage current, infrared radiation, as well as certain circuit breaker parameters and tests. To augment field tests, a program of accelerated life testing was also carried out. Apparent inconsistencies in data were identified as the result of environmental effects, primarily temperature and relative humidity. A series of environmental tests were conducted to develop correctionmore » factors that allow reference of measured parameters to standard conditions. A portable data collector was developed to aid in the accurate collection and analysis of laboratory and field data.« less