UPS and generator matching configuration scheme

When UPS is used in combination with generators, only a small amount of backup batteries need to be configured for UPS for use during switching. The conversion between generator and mains can be done manually or by setting an automatic switching device (ATS). When the mains fails, the automatic switching device (ATS) will automatically switch to the generator end, and the generator will automatically start after a certain time delay (the time can be set according to customer needs) to provide power guarantee.

In actual applications, different customers have different requirements for the availability of the power supply system, and the configuration methods of UPS and generators are also different. Generally speaking, the common ones are divided into single-machine mode and parallel mode. Each mode has its own characteristics. The following introduces them one by one:

A. Single machine configuration

According to the actual load power, select a matching UPS for single-machine operation. The schematic diagram of the power supply system is as follows:

The characteristics of this configuration are:

1. High cost performance. Although the availability of the power supply system is average, the system composition is simple and economical.

2. Generally speaking, there is no need to consider the later expansion of the system, and there is no need to use a parallel UPS, so the equipment utilization rate is high.

3. The system has a single point of failure.

The main components of the system are:

1. UPS host: The UPS host can provide high-quality power supply to the load regardless of the input mains power supply, and there is no output interruption when switching between mains power operation and battery operation; it has a built-in static bypass system to improve the availability of the UPS, and cooperates with the maintenance bypass switch to ensure uninterrupted power supply to the load when the UPS is shut down for maintenance.

2. Backup battery pack + battery DC circuit breaker: The backup battery is the energy source for powering the load after the mains power is interrupted. The stored energy is supplied to the load after being inverted by the UPS. The battery circuit breaker mainly provides overcurrent and circuit breaker protection for the battery pack to avoid battery damage and the expansion of UPS failure. In addition, the circuit breaker is manually disconnected during battery maintenance and replacement to ensure the safety of maintenance personnel.

3. Diesel generator: In high-power UPS systems, the battery configuration required for long backup time is often a large-scale, high-investment solution, so the diesel generator plus UPS solution is often considered; even if there are dual-circuit mains power supply, the backup diesel engine can still be used as the ultimate backup means, and it is more cost-effective than large-capacity backup battery packs.

The conversion between the generator and the mains can be done manually or by setting an automatic switching device (ATS). As for the capacity ratio of the generator and UPS configuration, due to interference such as harmonic feedback and sudden changes in load current of the UPS, the capacity of the generator is often required to be 2 to 3 times the maximum load of the UPS. At the same time, factors such as other loads carried by the generator should also be considered to determine its capacity.

4. Others: including related input and output power distribution systems.

B. Redundant parallel configuration

When the availability of a single-machine system cannot meet the requirements, two or more UPSs of the same power are often used in parallel to improve the reliability of the parallel system. The schematic diagram of the power supply system is as follows: