Erdpunktverlagerungen bei Transkommandotastung in Drehstromnetzen

Ohne Zusammenfassung     

SHORT METHODS FOR CHEMICAL ANALYSIS OF GLASS*

Analytical methods have been developed which shorten the time required for the determination of many of the constituents found in glass. These short methods have been worked into a procedure for the routine chemical analysis of container and sheet glasses. The determination of SiO₂, BaO, SO₃, R₂O₃, CaO, MgO, B₂O₃, Na₂O, and K₂O percentages on several samples can be made in a single day. Most of the experimental work has been done on Bureau of Standards glass No. 128, but results from several other glasses are included. Particular care has been taken to discover interfering substances and to eliminate errors from this source. The accuracy is comparable with that obtained from the use of umpire methods.     

Voltage Dip Protection with DC Motorstarter Coils

Continuous process plants are being designed today with fewer and larger components arranged in ``single train' configurations. Maintaining operating continuity with fewer components requires high equipment reliability. Motor controls for larger components are using magnetic contactors equipped with automatic undervoltage reclosing. A voltage dip where contactors drop open and reclose can be very serious because of the nature of motors and their driven loads during voltage transients. The reclosing of magnetic starters on motors with a decaying internal voltage is reviewed. A method of riding through voltage dips with dc coil magnetic contactors is described. Application of this method will depend upon the individual characteristics of each electrical system and the process that it serves.     

Corrosion inhibition of steel by hydrazine

The corrosion inhibition of steel in a closed system containing hydrazine at room temperature has been established. The steady-state potential measurements as well as weight loss measurements agree in indicating that hydrazine was found to behave in a similar manner to anodic inhibitors. A sharp ennoblement of potential occurs at concentration of 10^?2M accompanied by complete protection. The mechanism of inhibition by hydrazine is assumed to be due to its preferential adsorption on the local anodes inducing anodic polarization. After a certain critical concentration of hydrazine is reached complete blocking of the pores occurs which causes complete inhibition. For hydrazine-sulphate or hydrazine-chloride mixtures, a linear relationship is found between log hydrazine concentration and log maximum tolerated concentration of the aggressive ion. For hydrazine-sulphide mixtures, a concentration of 5 × 10^?2M hydrazine could tolerate a wide range of concentrations of sulphide ions.