3. Problems encountered in practical application of ATS and corresponding product solutions

As the economy develops, modern life and modern industry are less and less tolerant of power outages. Foreign industrialized countries (especially the United States) regard ATS products as part of the power supply, and are very cautious about the selection and use of ATS products. In the dual power emergency power supply system, first choose PC-level products, and the switch is not allowed to stay in the middle of the conversion process (that is, without zero position). The purpose is to increase the reliability of the power supply, especially for UPS.

Due to the different types of backup power and application environments, the ATS selection should also be different.

3.1 Problem 1: Switch synchronization problem

Ordinary ATS is not allowed to transfer with large motor or high inductance load. If the large motor load is switched during operation, it will be subject to huge mechanical stress when the power supply phase gap is large. At the same time, the overcurrent caused by the back EMF generated by the motor may cause the fuse to blow or the circuit breaker to trip.

Solution:

If you choose an ATS with phase angle synchronous detection and switching function, check whether the two power supplies are synchronized before switching if the two power supplies exist at the same time. When the synchronization detection is qualified, the ATS is allowed to switch. At this time, ensure that the back EMF and the about-to-input The mains potentials used are synchronized so that no inrush currents can blow fuses or trip circuit breakers.

3.2 Question 2: Neutral line switching problem when matching with UPS

Ordinary three-phase ATS has three-pole and four-pole classification, but the three-pole switch cannot meet the requirements of my country's power supply system that the incoming ATS must be four-pole switching and four-pole isolation. Although the four-pole ATS can meet the above requirements, it does not take into account the adverse effect of the four-pole simultaneous switching ATS on the user's load, especially the single-phase load in actual use. Since the ATS needs to be switched with load, the UPS will automatically switch to the bypass and cause the load to lose power due to the absence of the neutral line at the moment of switching in actual use. Raised and burned.

If you choose an ATS with the function of zero line overlap switching (later clutch first make technology), when the phase line ends are arced during the switching process, this structure can ensure that the zero line will not be separated temporarily; and when the switching is about to end, the phase line At the same time as the arc is drawn at the end, the structure can ensure that the zero line has been reliably contacted. During the whole switching process, the phenomenon that the neutral line is vacated will not occur.

3.3 Problem 3: Maintenance and Repair Problems

Once the ordinary ATS is put into use, it needs to be replaced as a whole if it fails. If you can choose an ATS with a modular design and the switch fails, you only need to replace the module at the faulty part to restore normal use, which can greatly reduce the cost of later maintenance. .

For some important loads, in order to ensure uninterrupted power supply, even if the ATS fails, it is not allowed to replace the switch. If the bypass isolation ATS switch is used, the faulty ATS can be replaced without power failure.

In a word, with the gradual development of ATS technology, it will definitely bring users more and more reasonable dual-power and multi-power switching solutions. Automatic transfer switch is a new product of power switching system. With the advancement of technology, it will inevitably develop in the direction of larger current, more voltage levels, higher switching reliability and more complete functions. UPS matching will be more widely used.