When people think of data center power, most immediately consider UPS systems, diesel generators, or PDUs. However, there is one often overlooked device that is absolutely critical: the DC power system for data center infrastructure, also known as a DC screen. Unlike the AC power that servers and IT equipment rely on, DC screens provide 110V or 220V DC power to support the facility’s backbone, including switchgear, protection relays, monitoring systems, fire alarms, and security devices.

Many wonder: if IT loads are AC, why do data centers need DC screens? The answer lies in the “invisible infrastructure” that keeps the data center operational even when the main AC power fails.

DC Screens: Powering the Nervous System of a Data Center

While servers, storage, and network switches rely on UPS systems for uninterrupted AC power, the data center itself depends on a robust infrastructure layer:

· Medium- and low-voltage switchgear operating mechanisms

· Automatic transfer devices / backup transfer mechanisms

· Protection relays and circuit breakers

· Power monitoring systems (SCADA)

· Battery room environmental monitoring

· Fire alarms, access control, and security systems

Most of these systems run on DC power for critical loads because they must operate even during AC mains failures.

For example, when both AC mains lines fail, a diesel generator typically takes several seconds to start. During this interval, the UPS maintains power to IT equipment. However, switchgear and protection relays—which control UPS input breakers, generator output breakers, and bus tie switches—require DC power to function. Without a working DC screen, even a fully charged UPS may not operate these switches correctly, potentially preventing generator startup.

In this context, DC screens are the final line of defense for data center operations—they safeguard control rather than energy.

Why Not Use AC UPS for Infrastructure Loads?

Technically, DC loads can be powered through an AC UPS system with rectifiers. However, this approach has significant drawbacks:

1. Single Point of Failure
If the UPS fails, all dependent DC loads also lose power. In contrast, a DC power system for data center infrastructure typically includes dual independent chargers and battery banks, providing redundancy and much higher reliability.

2. Battery Conflicts
UPS batteries are designed for short-term IT backup (15–30 minutes), while DC screens often have larger batteries designed for several hours of backup. Connecting infrastructure DC loads to the UPS would deplete backup power for IT equipment, reducing the available runtime.

This is why modern data centers adopt a dual-track power architecture: UPS systems power IT devices, while DC screens power critical infrastructure. Each system operates independently, ensuring optimized backup and reliability.

DC Screens vs. HVDC Systems

It is important not to confuse DC screens with High Voltage DC (HVDC) systems, which have recently gained attention as alternative UPS solutions.

While HVDC systems directly power servers as an alternative to UPS, DC screens provide reliable DC power for switchgear and monitoring systems, emphasizing long-life batteries, fault tolerance, and operational stability. Both systems may coexist, but they serve different layers of a data center’s power architecture.

Why Mains-Frequency Chargers Are Preferred in DC Screens

Data centers require high reliability, long service life, and low maintenance for their critical infrastructure. For these reasons, mains-frequency chargers are the preferred choice for DC screens:

· Strong shock resistance: Mains-frequency chargers with batteries can withstand frequent switching operations and high inrush currents.

· Long lifespan: Designed to match the typical 10–15 year lifecycle of data center infrastructure, reducing maintenance and replacement needs.

· Low electromagnetic interference (EMI): Provides stable DC output without affecting sensitive monitoring and control systems.

Although high-frequency chargers offer higher efficiency, they are less commonly used in mission-critical DC battery systems due to lower adoption in infrastructure loads.

Selecting a DC Screen for Your Data Center

When choosing a DC power system for data center infrastructure, consider the following:

1. Load Requirements: Identify all infrastructure devices that require DC power, including switchgear, fire safety, monitoring, and security systems.

2. Redundancy: Ensure dual independent chargers and battery banks for continuous operation.

3. Battery Life: Prioritize long-life DC battery systems capable of supporting several hours of backup.

4. Reliability: Opt for mains-frequency chargers for high reliability, low EMI, and compatibility with high inrush current applications.

5. Scalability: Ensure the DC screen can accommodate future growth in infrastructure loads.

Conclusion

In a data center, DC screens are like the autonomic nervous system of the human body: largely invisible but controlling vital functions. Without them, even the most advanced IT systems cannot operate safely.

From providing backup power for IT equipment indirectly to ensuring reliable DC power for switchgear and monitoring systems, DC screens have evolved from “optional” to essential components of modern data center power architecture.

For any data center operator seeking high reliability, redundancy, and operational control, investing in a well-designed DC power system is no longer optional—it’s a necessity.

About EverExceed

EverExceed is a global leading manufacturer of customized AC/DC power solutions， specializing in

UPS systems, DC power systems, lithium batteries, and energy storage solutions for data centers, telecom, solar, and industrial applications.Committed to innovation, quality, and long-term reliability, EverExceed empowers organizations to achieve high efficiency, resilience, and uninterrupted power supply. Guided by the brand motto: “Empower, Energize, Exceed the Energy you Expect forever,” the company continues to deliver solutions that exceed expectations and drive sustainable energy performance worldwide.