Rectifier, Electrochemical

In single-phase bridge circuits for ac connections and for very low ac output voltages below 5 V, single-phase center tap circuits are used as rectifier circuits for CP transformer-rectifiers. They have an efficiency of 60 to 15% and a residual ripple of 48% with a frequency of 100 Hz. A three-phase bridge circuit for three-phase alternating current is more economical for outputs of about 2 kW. It has an efficiency of about 80 to 90% and a residual ripple of 4% with a frequency of 300 Hz. The residual ripple is not significant in the electrochemical effect of the protection current so that both circuits are equally valid. 

Tank formation means that the cured positive and negative raw plates are inserted alternately in special tanks filled with fairly dilute sulfuric acid (generally in the range 1.1 to 1.15gcm 3) and positive and negative plates are connected, a number of each, in parallel with a rectifier. The formation process means that the active material of the plates is electrochemically transformed into the final stage, namely ... 

A classical setup for microwave conductivity measurements is based on the utilization of the waveguides. A simple installation consists of a microwave generator (typically a gun diode) which, when the Ka-band is used, can be operated in the frequency region of 28-40 Gc/s this is protected by an isolator against back-reflections from the rest of the microwave circuit. The microwave power is conducted by an attenuator across a circulator into the microwave conductor branch at the end of which the electrochemical cell is mounted. The microwave power reflected from the electrochemical sample is conducted via the circulator into the microwave detector. It typically consists of a diode that acts as an antenna, receiving the electrical alternating field, rectifying it, and con-... 

McCann JE, Pezy J (1981) The measurement of the Hatband potentials of n-type and p-type semiconductors by rectified alternating photocurrent voltammetry. J Electrochem Soc 128 1735-1740... 

The recognition of the lack of molecular-level information on electrocatalytic phenomena and the resolve to have this weakness rectified is now firmly established within the electrochemical and surface science communities. This is evidenced by recent international conferences and workshops devoted solely to electrochemical problems (11-4). It is also well-realized that electrochemistry cannot advance further unless the practitioners in this field begin to view electrodesolution processes from a molecular-level perspective. 

For large electrochemical installations mercury-arc rectifiers are used whioh have proved valuable whereever strong direct current and relatively high voltage is required (above 300 V). In this case there is a loss of energy whioh is in proportion to the voltage necessary to overcome the arc resistance (20 to 30 V). As this voltage depends neither on the current nor on the total output... 

Much of the inefficiency in the cell results in heat generation a cell will heat itself almost to boiling when fed brine at about 40°C. The self-heating tends to lower the cell voltage because the electrical resistance of the cell decreases with increasing temperature. As modern rectification equipment (transformers, controllers, and rectifiers) is very efficient, the conversion of AC electricity into electrochemical products is essentially dependent on the cell efficiency. Typically, AC-kWhr/lb product = 1.03 DC-k Whr/lb product. 

Zviagin and Liutovich (11) found similar minimum values for p-type Si as we did for the Ge samples. The theoretical curve of the Russian authors is calculated on the assumption that the minority carriers are depleted. This is possible for a p-type semiconductor only in the case of cathodic polarization. Since the Russian authors did not take into account the possibility of enrichment of the minority carriers, they did not get a distinct minimum of the theoretical capacity-potential curve. We found the minimum for n-type Ge under reverse bias, i. e., under anodic current. This result is to be expected (in contrast to a common rectifier) as long as the resistance across the phase boundary (R ) is high compared to the recombination rate or the rate orformation of free carriers. It is to be expected, in other words, as long as the electrochemical potential of the free carriers remains nearly constant across the space charge up to the surface. The Russian authors point out that the measured capacity is not equal to the space charge capacity, but should be related to it. This relationship is indicated by the measured frequency dependence of the measured impedances. It is in agreement with our assumption that the... 

Since the modified films act as insulators <0.70 V, there is no response when the redox potentials of the reduced species in solution are lower than this value. When this limiting potential is reached, the film becomes conducting via electron hopping, and the reduced species can be rapidly oxidized, leading to a sharp, unidirectional, electrochemical response. In this case, an electric rectifier response is observed (250). Note that when the redox potentials of the reduced species match... 

The heart of all electrochemical processes is the cell room this contains the electrochemical cells, the piping connecting the cells to the electrolyte containers and their pumps, the rectifiers and power distribution, the process and safety control, and, last but not least, parts of a building. 

Srinivasan, V. and Lipp, L. (2003) Report of the Electrolytic Industries for the Year 2002. J. Electrochem. Soc., 150, K15—K38. National Materials Advisory Board (1986) New Horizons in Electrochemical Science and Technology, NMAB 438-1, National Academy Press, Washington, DC. Aviram, A. and Ratner, M.S. (1974) Molecular Rectifiers. Chem. Phys. Lett., 29, 277-283. 

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