Hyon Song Chol, a section head at the Faculty of Electrical Engineering, has developed an 800A electrolytic power unit where polarity can be reversed.
Polarity reversion technology can prevent resistance from getting larger and speed of electrolysis from getting slower, due to the silver oxide film formed on the anode during gold refining.
A periodic negative bath voltage makes a silver oxide film separate from the anode. As a result, the fineness of gold and the speed of electrolysis increase with less power consumed.
The polarity reversible electrolytic power unit consists of a full-wave rectifier, a high frequency transformer and a bridge drive unit, a rectifier and filter, and a polarity reversing unit.
The bridge drive unit of the high frequency transformer drives it at 20kHz using phase shift and a soft switching mode.
The voltage at the secondary side of high frequency transformer is then full-wave rectified and filtered, becoming two DC power sources with separated ground.
From these two DC power sources, a negative and a positive voltage are alternatively output periodically by changing the channel with two thyristors at the polarity reversing unit. The polarity reversing unit is constructed in the way of minimizing voltage drop on the current routine, as well as befitting the feature of the thyrister that costs less per unit current but is free from self-closing.
Compared with previous control rectifiers, the voltage distortiong rate is decreased by 5%, the cost by 60% and the weight by 30%.
This device can be used not only as an electrolytic power source unit for non-ferrous metal refining but also as a plating power source unit.
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