According to the nature of the current delivered, the transmission is divided into AC transmission and DC transmission. In the 1880s, the first direct realization of DC transmission. However, since the voltage of the direct current transmission is difficult to continue to improve under the technical conditions at that time, the transmission capacity and efficiency are limited. At the end of the 19th century, DC transmission was gradually replaced by AC transmission. The success of AC transmission has ushered in a new era of electrification in the 20th century. Three-phase AC transmission is widely used at a frequency of 50 Hz (or 60 Hz). Since the 1960s, there has been a new development in direct current transmission, which is combined with AC transmission to form an AC-DC hybrid power system.
Overhead sectional door most widely used for loading areas on all types of industrial premises and Designed with a curved overhead track, these vertically-opening sectional doors can be installed in areas with reduced head room. They provide heat and sound insulation with its composite panel construction.
The counterbalance and cable system provides quiet and straight forward operation for manual doors. Electric operation is available for larger applications that can incorporate many alternative operator options to suit all client requirements.
The standard outer panels are manufactured from 0.5mm thick, high quality zinc coating to BS EN 10147
For the best weather protection the sectional door panel has an interlocking hinged joint integrating a high quality seal the full length of the panel.
A counterbalance system is incorporated into the sectional overhead door to ensure efficient and effortless operation.
The counterbalance comprises of springs mounted on a steel shaft that are high tensile helical wound steel. It has been heat treated for enhanced performance for around 50,000 cycles.
Reducing shaft friction is achieved with the aid of brackets and guide rollers incorporating highest quality sealed bearings.
Overhead Sectional Door,Overhead Sectional Garage Door,Automatic Overhead Sectional Door, Overhead Insulated Garage Door
Shenzhen Hongfa Automatic Door Co., Ltd. , https://www.pvchighspeeddoor.com