UPS power supply manufacturers explain in detail the decentralized bypass and centralized bypass of UPS. There is a set of relays at the mains input terminal of the UPS. There are two relays, one is the main circuit and the other is the bypass. Generally speaking, the frequent switching of UPS power to the bypass has no protective effect on the UPS itself, which reduces the stability. UPS power supply manufacturers come to explain in detail the two modes of UPS.
UPS power supply manufacturers explain UPS decentralized bypass and centralized bypass in detail
At present, the static bypass of UPS power system mainly has two modes, namely, decentralized bypass mode and centralized bypass mode. As the name implies, the decentralized bypass means that each UPS unit in the UPS system has a static bypass, and the centralized bypass means that the entire UPS system has only one bypass system.
Decentralized bypass means that in a set of UPS system, each UPS unit constituting the system has a bypass, and the capacity of the bypass is the same as that of the UPS unit. When the system transfers to the bypass, the bypass of the UPS unit is activated at the same time. From the perspective of the entire system, it is equivalent to multiple bypasses in parallel to supply power to the load.
Centralized bypass means that there is only one bypass in a set of UPS system, and the capacity of the bypass is equivalent to the system capacity. When the UPS system transfers to bypass operation, the bypass starts to supply power to the load. Both bypass methods have applications and have their own suitable scenarios. When selecting a suitable bypass method, consider the actual use.
The availability of UPS decentralized bypass is much higher than that of centralized bypass, so decentralized bypass is more suitable for scenarios with high availability requirements. When a short circuit occurs in the actual power distribution system, the peak value of the circuit current will be limited, and an appropriate number of decentralized bypasses can meet the short-circuit current. However, if the number of decentralized bypasses is too large, it will lead to risks, and the actual use scenarios need to be evaluated and calculated.
The bypass control technology of UPS power modular and large-capacity models is mainly divided into centralized bypass mode, one set of bypass for the whole set of equipment, and decentralized bypass mode means that each power module has a separate bypass channel. The centralized bypass has strong overload capacity and high reliability. The decentralized bypass has the characteristics of scalability and low cost, but the reliability is not as good as that of the centralized bypass.
For the decentralized bypass mode, on the surface, due to the decentralized layout, it is similar to the redundant design when the UPS power supply module is redundant. One bypass fails, the other bypasses can still work. In fact, this kind of dispersion is fundamentally different from redundancy. The main component of the bypass is SCR.
Because of the large discreteness of the devices, when the UPS power system works in bypass mode, each bypass is basically impossible to be in a current sharing state; and in order to maintain the integrity of the voltage waveform output by the bypass, no switching action is performed in the bypass mode. , It is difficult to control the current, and it is difficult to control the uneven current flow within 25% only by relying on the natural current sharing. Modules with large currents are likely to shut down due to bypass overload, which affects the continuity of system power supply.
In fact, in the application of traditional tower UPS power supply, when the number of parallel units exceeds four, in order to avoid the problem of uneven current flow in the bypass, a centralized static bypass system is generally required. Because of the limitation of the bypass system, it is difficult for the UPS with the decentralized bypass system to have better scalability.
UPS uninterruptible power supplies include static bypass and maintenance bypass. The static bypass passes through the internal circuit of the UPS. The UPS is in operation during the lead-through process, while the maintenance bypass is to completely trip the internal components of the UPS and maintain the bypass. When the circuit is turned on, the UPS can be shut down for maintenance and other activities. In fact, there is no essential difference between the two bypasses and the mains.
