Fast transfer test of power station auxiliaries
There has been much work done concerning the analytical and theoretical analysis of bus transfers, most of this pertaining to the induction motor during transients; however, very little has been published presenting experimental data of such a transfer. In this paper data is presented which was taken during and after a bus transfer on a 450 MW fossil fired unit. The data shows the validity of the models, but also indicates that the synchronous motor is more of a concern than previously thought.
A Simplified Procedure for Determining the Auxiliary Bus Voltage and Angle During Bus Transfer
During a power station auxiliary bus transfer the bus residual voltage and angle relative to the reserve bus voltage are critical for the first .5 second. A procedure is presented that determines the auxiliary bus voltage during the critical period of the bus transfer. For this simplified procedure a gas fired steam turbine generator auxiliary system is the test case used. The procedure is equally applicable to a nuclear steam turbine generator auxiliary system. The effect of residual motor current is reviewed. Motor speed may also be determined with reasonable accuracy.
Thermal stability of reconstituted collagen fibrils. Shrinkage characteristics upon in vitro maturation
Thermal stability measured as area shrinkage without tension during heating was determined for membranes of collagen fibrils reconstituted from solutions of highly purified rat skin collagens. Shrinkage in per cent of area at 25 degrees C and shrinkage temperature were quantitated in a standardized way and determined as a function of in vitro maturation time for 11 to 104 days after aggregation for the collagen membranes. Similar to reports on intact rat skin, shrinkage temperature remained constant and shrinkage per cent declined with a rate decreasing with time during maturation. Solubility in water at 80 degrees C for 2 hours was 95-96% and remained unchanged for the maturation time (about 2 months) studied. The decreased shrinkage reflecting a lower degree of collapse is ascribed to an increasing thermal stability of the membranes during maturation. Development of heat-stable bonds in the reconstituted collagen fibrils is taken up to be amenable to this increased stability. Similarity in changes of shrinkage characteristics during in vivo and in vitro maturation indicates that maturation changes in reconstituted collagen fibrils reflect those occurring in intact collagen during in vivo aging.