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A Guide to Data Center Circuit Breaker Design and Deployment
Data center circuit breakers protect equipment, but correct hardware management is key to reliable operations. Find out how to optimize design and deployment.
5 Min Read
Data center circuit breakers trip almost instantly to prevent equipment damageImage: Alamy / Data Center Knowledge
Just like homes and offices, data center circuit breakers are vital to helping regulate electrical current and protect equipment from overloads. But unlike most other facilities, data centers are subject to some unique challenges when it comes to circuit breaker design and management.
To optimize the use of data center circuit breakers, this guide covers how they function, the challenges they may present, and the best practices for designing and installing circuit breaker systems.
What Are Data Center Circuit Breakers?
Data center circuit breakers are components of a data center’s electrical system that protect equipment for excess current and electrical faults.
Just like the circuit breakers that you’d typically find inside an electrical panel box in your home’s basement or utility closet, data center circuit breakers trip – meaning they break the connection within an electrical circuit – in response to problems within the circuit.
When circuit breakers detect excess current or faults, they typically trip in just fractions of a second, which is fast enough to prevent serious damage from occurring to equipment connected to the circuit.
Multimode fiber switch and circuit breakers inside power case (Image: Alamy / Data Center Knowledge)
Where Are Data Center Circuit Breakers Located?
Typically, data center circuit breakers control the flow of electricity to Power Distribution Units (PDUs) and Remote Power Panels (RPPs). Servers and other equipment plug into the PDUs and RPPs, with circuit breakers acting as intermediaries between the main electric source and the PDUs and RPPs that connect to IT equipment.
That said, some PDUs feature built-in circuit breakers, which theoretically eliminates the need for an external circuit breaker between the power source and the PDU (although having an external circuit breaker in addition to a built-in breaker is acceptable).
Rarely, breakers may exist between PDUs or RPPs and individual servers, especially in cases where technicians want to isolate the electrical connection of a specific device.
Challenges in Data Center Circuit Breaker Design and Management
Although circuit breakers in data centers work in the same way as circuit breakers in other types of facilities, data centers are subject to some special challenges that can complicate circuit breaker installation and management, including:
The need for rapid reset: When a breaker trips in a data center, it’s typically critical to reset it as quickly as possible to prevent servers from crashing. (Often, servers can remain powered for a short period by an uninterruptible power supply, so if you reset the breaker quickly enough, you’ll avoid server shutdowns.) This may not be a priority in other settings, where catastrophic results will not occur if it takes more than a few minutes to reset a tripped breaker.
Breakers as single points of failure: If a breaker controls the flow of current to a PDU or RPP that serves multiple servers, all the servers may disconnect if the breaker were to trip.
Unpredictable future energy requirements: The future electricity requirements of servers can be challenging to predict, and breaker and circuit designs that work well initially may create issues later. For example, due to the increased energy needs of AI workloads, a breaker that was adequate for conventional servers may begin tripping when it regulates current to servers that handle energy-intensive AI tasks.
Ambient temperatures impact performance: The sensitivity of some circuit breakers is impacted by ambient temperatures. This means that in hot environments – like server rooms – breakers can become more susceptible to tripping in cases where no electrical fault has actually occurred.
In short, circuit breakers in data centers can be more challenging to manage and can behave in less predictable ways. At the same time, the consequences of unexpected circuit breaker operations tend to be more serious inside data centers, since virtually nothing inside a data center will function without a reliable supply of electricity.
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Best Practices for Managing Data Center Circuit Breakers
To ensure that circuit breakers inside a data center do their job reliably without unnecessarily disrupting the flow of energy, consider best practices like the following:
Avoid unnecessary breakers: As a rule, don’t install more breakers than you need. Circuits with more than one breaker have more places where something could go wrong, leading to issues like the powering down of a server.
Consider breakers for individual servers: The exception to the practice we just described is cases where an individual server (or other system) is especially susceptible to causing electrical faults. In that situation, installing a breaker just for that server can help prevent a problem with the server from affecting other devices, since the server’s dedicated breaker should trip before the issue affects the main breaker.
Locate breakers centrally: Instead of spreading breakers throughout your data center, locate them in a central place. This makes it easier for staff to determine which breaker has tripped in the event of a failure.
Use electronic breakers: Some circuit breakers feature electronic trip systems. These are less susceptible to unpredictable behavior due to issues like ambient temperature variations, which makes them more reliable for high-stakes settings like data centers.
Use breakers with automatic reset features: Advanced circuit breakers offer automatic reset features that allow them to restore the flow of electricity to a circuit. This capability reduces the risk of server failures due in cases where a breaker trips due to a short-lived problem and can safely reset itself automatically afterwards.
Deploy UPS units: As noted above, an uninterruptible power supply (UPS) can provide temporary power to servers if a circuit shuts down. UPS units are a critical safeguard for ensuring that unexpected tripping by a breaker won’t cause servers to crash suddenly.
Invest in power monitoring: Power monitoring and metering systems track overall energy usage within data centers. In addition to helping to identify opportunities for reducing power consumption and improve sustainability, power monitoring can provide visibility into issues that affect circuit breakers, such as circuits whose current flow routinely approaches the maximum current allowed by a breaker.
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