Uninterruptible Power Supplies (UPSs) are designed to provide power protection in the event of power interruption or failure. However, some applications are so vulnerable to downtime that they require redundancy in UPSs and associated components. In this article, we’ll look at two of the five simple uninterruptible power supply configuration options that provide the greatest possible security.
UPS Design Configurations
Some of the most commonly used UPS design configurations are listed in order of increasing levels of redundancy below:
- Capacity or N design
- Isolated redundant
- Parallel redundant (N+1)
- Distributed redundant
- System plus system (2N, 2N+1)
Although capacity or N configuration is by far the most common, it will not be passed on to large data centers or financial organizations that simply cannot afford downtime. For them, it is usually either a redundant distributed system or a system plus system.
Uninterruptible Power Supply: Distributed Redundant
Distributed redundant designs were developed at the end of the 1990s to provide full redundancy capabilities at a lower cost than the simple purchasing of multiple UPSs.
The architecture uses three or more UPS modules with different input and output feeders. Output busses connect to the downstream critical load via multiple PDUs and, in some cases, static transfer switches (STSs). The STS has two inputs and a single output. Usually, it takes power from two separate UPSs and supplies the load with the conditioned power of one of them. If the primary uninterruptible power supply fails, the STS can pass the load to the secondary UPS in approximately 4 to 8 milliseconds, providing power safety at all times.
There are several options for configuring a distributed redundant architecture, but all of them should allow for simultaneous maintenance and reduce single failure points. Configurations may often become complex, so care must be taken to ensure that the devices are loaded equally.
Uninterruptible Power Supply: System Plus System
The system plus system model is perhaps the most reliable system in the industry, intended to ensure that loads never run on “raw” utilities. It goes by different names, like:
- Isolated Parallel
- Multiple Parallel Bus
- 2(N+1), 2N+2
- [(N+1) + (N+1)]
As with the distributed redundant model, there are several choices for configuring a system plus system model with varying complexity degrees. The basic concept is that each electrical equipment piece can fail or be switched off without requiring any critical load to be transferred to the power station. This also includes the use of bypass circuits that allow parts of the system to be shut down and bypassed to an alternative power source to retain uninterruptible power supply power at all times. In short, the architecture needs two power paths to all critical loads and full redundancy from the service entrance all the way to critical loads.
Not surprisingly, the system plus system design is the most costly design of the five due to the amount of redundant components and their relative energy inefficiency. However, its expense can be justified on the basis of the value of the loads it protects. Indeed, several of the world’s largest organizations are using it to secure their vital loads.
Today’s Emerging Needs Of Uninterruptible Power Supply
Human standards of high availability are changing. In simple terms, High Availability represents the notion that the device can operate when it is needed. Some examples of high availability in our daily day-to-day life are –take money from ATM when we need to, start the engine of a car with an ignition switch, hail a taxi, book a flight, and check the traffic on the freeway you frequent.
Similarly, every commercial, institutional, and industrial facility needs power backup and 100% uptime of productivity to ensure the organization maintains its competitive edge. However, to implement appropriate solutions, you must find your facility’s unique requirements, be it residential or commercial. For the same, it is recommended that you consult a leading UPS solutions provider or consult qualified electrical consultants!