COMPARISON OF AVAILABILITY BETWEEN 4.2-K AND 77-K SMES-CONCEPTS

The influence of nitrogen cooled superconductors to the availability o f a 100 kWh SMES concept has been analysed. A conceptual design of a r eference unit at 4.2 K has been used as a basis of the study [1]. This kind of unit with independent control of real and reactive power is s uitable for load management for example in foundries. The comparison o f availability has been done between 77 K and 4.2 K concepts. In order to do this analysis one has to assume that the mechanical and electri cal performance of a HTS cable is equivalent to that of a conventional one. The method used is based on the failure modes, effects and criti cality analysis (FMECA). Fault trees describe the outage logic based o n the functional analysis. Event trees clarify the consequences of the primary events and criticality of these consequences is expressed as a system down time. The existing data base is extremely limited, so ex trapolation of data from other technologies can not be avoided.