N+1 Redundancy Explained

N+1 redundancy is critical for semiconductor, military, and industrial applications, as it ensures a company's system continues to operate in the event of component failure. Without N+1 redundancy, if one of the modular power supplies fails it can lead to a complete shutdown of the entire power system. An N+1 system offers an additional module, if one module fails the system can continue to support the load, increasing your system's reliability and reducing the risk of service interruptions.

N+1 Redundant System Design

One of the most popular ways to provide redundancy to industrial systems is with an N+1 redundancy system. ‘N’ refers to the minimum power modules required to meet the load requirement for a system to operate. In industrial applications, a system that contains the minimum power modules doesn't offer redundancy and won't have the ability to function if a failure occurs. This type of system leaves a company vulnerable to major power interruptions if a system issue occurs.

With an N+1 system, the ‘N’ still stands for the minimum number of independent modules required for a system to operate. The "1" in this equation refers to the number of additional components that act as an independent backup that allows the system to operate as intended if one of the modules within ‘N’ fails. The additional backup makes it possible for a system to function during component failure, as the system will still have alternative paths to use. For example, if a system requires 8 power supply modules to operate, an N+1 power system may include 9 power modules. If one module fails, the power system can continue operation with the additional module.

Redundant System Design


System Power Requirements: 115kW

Each Module: 16.5kW

Number of modules needed in the system (N): 7

Number of modules needed for an N+1 system: 8


Is There a Difference Between N-1 vs. N+1 Redundancy?

While it might seem contradictory, N-1 and N+1 redundancy refer to the same thing. The German power system refers to their use of N+1 redundancy as N-1 Sicherheit. 

Cold vs Hot Standby N+1 architecture

Cold standby requires an operator to notice there is a failure or alarm and bring up a new module. In this case, the ‘1’ is present but needs to be brought up to resume operation of the system.

N+1 Redundant System Design (2)


System Power Requirements: 4 Channels 66kW

Number of channels needed in the system (N): 4

Number of channels needed for an N+1 system: 5


Hot standby offers continuous operation with no interruptions. The ‘1’ is already running and immediately takes over when there is a failure detected without an operator’s assistance.

The Importance of N+1 Redundancy

Investing in an N+1 redundancy system for your semiconductors or industrial power solutions can provide several advantages, including:

  • Improved trust and dependability: One of the key advantages of N+1 redundancy is that it makes your systems much more reliable. Since you can trust them to continue operating effectively if an issue occurs, you can have greater peace of mind.
  • Reduced risk of service interruptions: Service interruptions can reduce customer satisfaction, lower productivity, and increase costs. With an N+1 system, it's unlikely that both your primary system and your backup system go down at the same time, putting you at a much lower risk of service interruptions.
  • Protection against anomalous behavior: When you notice strange or anomalous behavior in your system, an N+1 system helps you take action against it. You can switch over to the backup system while you determine what's causing the anomalous behavior and fix it, preventing an interruption in operations.
  • Adequate fault tolerance established: Implementing an N+1 system helps you create a fault tolerance architecture. With this architecture, a fault in your primary system won't result in total system failure. With a hot standby N+1 architecture rather than a cold standby option, you can ensure changing to the backup unit doesn't cause the system to fail.

Copy of MRIDC

N+1 Redundancy Applications

N+1 redundancy systems are critical in semiconductor applications where downtime can result in high costs. Besides N+1 redundancy's applications in semiconductors and other industrial settings, it's also commonly used for aerospace applications, automobiles, and electric power systems. For example, a business may have an N+1 redundancy system to ensure its servers and hardware have a backup power source if the primary power modules fail to operate.

In the aerospace industry, many companies use N+1 systems to improve their aircraft's integrity and safety, as component failure could lead to major operational issues. You can also find N+1 systems in the automotive industry, such as the implementation of an emergency brake to provide drivers with another braking source if the main brake system fails.

Is an N+1 Redundancy System Right for You?

When deciding if N+1 redundancy is right for you, you'll want to consider the cost of downtime in your system. An N+1 redundancy system is an excellent option to prevent downtime, but there are also other redundancy systems available today.

You may have a choice between N+1 vs. N+N redundancy for power supplies. In the N+1 model, a system's components have a single, independent backup component. An N+N redundancy system sometimes referred to as a 2N redundancy system, has a duplicate component for every component in the system. There are also 2N+1 redundancy systems, where a company has a duplicate component for all their primary system's components and a single backup component.

While N+N and 2N+1 systems help provide backup in case of system failure, an N+N system can cost significantly more. It can also be a waste of resources due to the low risk of all a system's components breaking down at once. A 2N+1 redundancy system gives greater protection and allows companies a chance to repair their primary system without shifting over to their duplicate system. However, this system also comes with higher costs and potentially wastes more resources than an N+N system.

To stay cost-competitive while still having a reliable solution, companies often turn to N+1 redundancy instead. An N+1 system can save on maintenance and repair costs since you won't have to dedicate staff to maintaining a duplicate system. N+1 systems are often an effective and affordable choice for businesses.

If you want a little more protection for your system, you might select an N+2 system, where you have two backups for all your system's components. This choice can be a good middle ground between N+1 and 2N redundancy systems, but you'll need to evaluate your system's performance before you invest in an extra backup. If your system isn't likely to have multiple components fail at once, an N+1 system is still an exceptional choice.

Choose Astrodyne TDI for Your N+1 Redundancy Needs

At Astrodyne TDI, we provide high-quality power supplies for semiconductors and other industrial applications. Alongside our AC/DC and DC/DC power supply offerings, we can also craft custom power supplies to ensure you receive a solution that meets your exact needs. We understand the importance of proper redundancy architecture and can design N+1 redundancy power systems with hot-swap capabilities. The hot-swappable feature allows the end-user to replace a power module without the need to interrupt operation. Astrodyne TDI N+1 redundancy systems with hot-swap features are available with both liquid-cooled and air-cooled power supplies. Power solutions with N+1 redundancy are regularly built for semiconductor applications. We’re happy to work with you to provide the perfect redundancy option for your system.

Find out more about our power supplies for semiconductor equipment today. If you have questions or want pricing information, feel free to contact us or request a free quote.