Silicon rectifiers

FIG. 17-75 Schematic circuits for silicon rectifier sets with saturable reactor control, a) Full-wave silicon rectifier, (h) Half-wave silicon rectifier. Industrial Electrostatic Vreci])itation, Addison-Wesley, Read-... 

Ohl demonstrated his results to Kelly early in 1940 Kelly felt that his instincts had been proved justified. Thereupon, Bell Labs had to focus single-mindedly on radar and on silicon rectifiers for this purpose. It was not till 1945 that basic research restarted. This was the year that the theorist John Bardeen was recruited, and he in due course became inseparable from Walter Brattain, an older man and a fine experimenter who had been with Bell since the late 1920s. William Shockley formed the third member of the triumvirate, though from an early stage he and Bardeen found themselves so mutually antagonistic that Bardeen was sometimes close to resignation. But tension can be productive as well as depressing. 

Diode, silicon rectifier, 1N4001, 1 amp. Jameco, electronics supplier 14859CR 2-10... 

W.A. Reynolds Corporation (Phila., Pa.) type 300.12 Reycor silicon rectifier with self-contained powerstat control providing 300 amps at 12 V DC output with a 230 V, 3 phase, 60 cycle AC input. Unit had maximum of 5% ripple and was fan cooled. Cabinet size 22 in. X 17 in. D x 241/2 in. H. 

The cellhouse is composed of 3 lines with a total 324 cells and 3 rectifier circuits. Figure 6 shows the outline of the facilities. The No. 1 line was 18 cells/row x 8 rows for a total of 144 cells a silicon rectifier with 32.5 kA 550V was used. The No. 2 line had the same facilities as the No. 1 line. The No. 3 line was composed of 18 cells/row x 2 rows for a total of 36 cells, and a thyristor rectifier of 140V 36 kA was used. Of these cells, 2 rows, 36 cells, were normally short circuited for cell maintenance. 

In rectifiers with fuses as protection against overloading and short circuits, only those of the type recommended by the supplier must be used. This is particularly the case with silicon rectifiers. Potential-controlling rectifiers can be protected against overloading and short circuits by limiting current in the control circuit. 

Many dc generators driven by motors have been installed in industrial plants, such as steel mills, to provide power for variable-speed drives. However, the advances in static silicon-rectifier dc power sources have reduced the market for dc generators primarily to replacement and repair parts, with very few new installations. 

Since 1960 the direct current for electrolysis has been provided exclusively by silicon rectifiers. A set of rectifiers can supply up to 450 000 A. Voltages up to 4.0 kV per diode are feasible, but usually for safety, a peak a.c. voltage of 1500 V, corresponding to a d.c. output of 1200 V, is not exceeded. Liquid cooling of the diodes permits a compact design, and self-contained equipment reduces leakage losses. Modem electrolysis cell plants also use continuously variable thyristor converters in place of silicon diodes [64]. 

The silicon rectifiers (oil and water-cooled) have longer lives and higher efficiency compared to selenium rectifiers. The oil-cooled types are not susceptible to damage by dust and dirt. They are 20-50% smaller in size than the selenium rectifiers. 

---