Engaged in chromium plating work of electroplating people all know that chromium plating requires a stable DC power supply, if other conditions are the same, the hardness of chromium layer with low pulsation rate of DC power supply is the highest. If single-phase half-wave power supply is used, although the coating will not crack, the coating has no brightness, low hardness and poor coverage ability, so single-phase half-wave power supply cannot be used for chromium plating. For example, chromium plating with single-phase full-wave power supply is not applicable because of its less cracks and poor coverage ability. Considering the external brightness, hardness and covering ability of the coating, the DC power supply for chromium plating is the most ideal one with flat waveform power supply above three-phase full wave. Therefore, in addition to meeting the power-related parameter requirements such as current and voltage, the rectifier with chrome plating configuration must also ensure that the ripple coefficient is less than 5% under low load conditions, and the products with high requirements must be less than 3%;

    The so-called ripple coefficient is the ratio of AC ripple voltage contained in the DC output by rectifier to the output voltage. All DC obtained by rectification and filtering will contain certain AC components, and the amount of AC components depends on rectification mode, voltage regulation method, filtering and leveling effect, etc.

    According to the development history of chrome-plated DC power supply, Experienced from DC generator, selenium rectifier, silicon rectifier, thyristor rectifier to high frequency switching power supply, Among them, the diode silicon rectifier lasts for a long time, According to the rectification mode, it can be divided into three-phase full-wave rectification and three-phase bridge rectification. The voltage regulation methods include induction voltage regulation, autocoupling voltage regulation, double reverse star-band balance reactor voltage regulation, etc. The thyristor (thyristor) voltage regulating rectifier has the characteristics of simple voltage regulating mode, However, because the voltage regulation adopts the way of adjusting the conduction angle, If satisfactory ripple coefficient is needed, its power factor is low and has a great influence on the power grid waveform. Because most of them need to use impulse current, the thyristor is often partially conductive during normal chromium plating, especially when the plating area of the workpiece changes greatly, it is not suitable to use thyristor rectifier equipment. The high-frequency switching rectifier developed in recent ten years is popular because of its small size, high conversion efficiency, good energy saving effect, stable output and easy adjustment. It adopts high-frequency switching diodes for rectification, but the ripple coefficient of power supply produced by each

Last：Measures to reduce chromic acid regeneration and prevent aging by chromium plating

Next：Chromium plating test requirements