Compared with DC and AC, everyone has heard of it, but most of the household refrigerators use AC, and DC is rarely used, but DC freezer is an application of DC.
The DC transmission adopts a two-wire system with earth or seawater as the return line. Compared with the three-wire three-phase AC transmission, under the same conditions of the same cross-sectional area of the transmission line and the same current density, it can be transmitted even without considering the skin effect. The same electric power, while the transmission line and insulation materials can save 1/3.
A steady direct current does not produce electromagnetic radiation. Because it only produces electric fields and does not produce alternating magnetic fields, even ultra-high voltage direct currents are only strong enough to ionize the air and emit light. At this time, optical radiation is emitted by air ionization, not Wire does not generate electromagnetic waves.
Many big size freezer uses direct current, which has its own unique advantages. Therefore, although most electrical appliances use alternating current, the use of direct current still has its own characteristics.chinafreezers.com