Dual power automatic transfer switch domestic and international standards dual power automatic transfer switch IEC60947-6-1 relevant international standards and national standards GB / T14048.11 have relevant personnel are aware of the criteria necessary to automatically switch to the requirements and constraints of ATSE selection and use. However, considering the many practical engineering and construction can meet the requirements of a given load, this paper, the application of practical engineering analysis. Combined with the actual number of specific projects and the load on this issue by listing a number of practical projects often encountered, for the selection of ATSE be breaking capacity on points - short-circuit withstand capacity in the power supply system, the short-circuit current is inevitable, so When selecting an electrical switch, short-circuit current and its impact must be considered, for the PC level ATS, load switch, disconnecting switch, AC contactor, which do not have the protection of the switch, the case of short-circuit failure, which, fuses action resection short-circuit current. So they do not have their own protective function switch in the choice, not only to consider the rated current value, prospective, the short-circuit withstand capacity includes the "tolerance time" and "withstand current" two concepts wholesale dual power supply unit quotient, which is within the range of how long can we know when the current through a conductor is to heat, does not consider the current changes brought about electromagnetic effects (dynamic stability), the general switch burned square of the current flowing through a conductor and proportional to the time, the role of the conductor current increases, the longer the dual power system supplier, the more heat generated. If we want to switch the melting point, or shortening the time t. In theory, increase the melting point of the switch is to choose a high melting point metal (e.g., gold, tungsten, silicon alloys, etc.) make contact, increasing the cost of the switch and a touch switch and a plus increased size of the switch, and a high melting point alloy technology for foreign companies are confidential, so it is not easy to achieve. Reduction off the circuit breaker or fuse and other considerations fast. Dual power switch conversion time and standby power requirements for the introduction of ATSE's purpose is to allow the load without power outage or as little as possible. So the choice is critical to know the load ATSE standard national design specification does not give a clear indicator ATSE so there is no clear national standards requirements. Dual power switch principle is: trying to capture the self-excitation voltage and supply voltage phase, so that in the same phase (excitation voltage and the supply voltage in the same direction dual power supply unit purchase, there will be no change in the current extended to ATSE. Functionally, is to do the same phase converter has the following advantages:. ⑴ motor is only momentary interruption, motor starter will not trip the self-excitation voltage parameter table is usually self-excitation voltage of the motor when the power supply will be high again. However, because it is the same phase switching, when only the electrical load switch, does not require control of the generator, no additional connection to the generator. specialized in phase detector controls the entire conversion process. ATSE, but also in the realization of this function have the following problems: ⑴ how to capture self-excitation voltage and supply voltage phase; captured later how to catch the same dual-phase power supply unit, and how to complete the conversion in a short enough time to the current international advanced ATSE manufacturers. approach is: as a constant and fast conversion speed is fast enough when the conversion (eg 80ms with advance way to solve the second difficulty addition, with constant conversion fast enough, as long as the power to capture the two. phase waveforms can be left the way power supply voltage waveform voltage is the same, so in a short enough time, we can approximate the probability of catching considered self-excitation, the phase angle difference may be limited in certain range (for example, ± 30 °) rather than 0 °, that Japan Kyoritsu HTS type ATSE greater impact, so it should be seriously considered. Dual power supply unit Buying, dual power supply units, only Thai Industries Thai Industries Limited only by the Shanghai Branch Yueqing provided. Thai Industrial Co., Ltd. Yueqing Branch (www.cnats.cc) strong, credible, in Wenzhou, Zhejiang switch industry has accumulated a large number of loyal customers. The company better work attitude and continuous improvement of innovative ideas Shanghai only Thai Industries will lead only into the brilliant and you work for a better future!