For data centers, power distribution is critical, and the power supply to the equipment is managed through a Power Distribution Unit (PDU). The PDU is not just a regular power distribution board; it supplies power to servers, devices, or racks, allowing us to manage and maintain IT equipment within the rack. Therefore, choosing the right PDU for the data center is necessary, and several factors need to be carefully considered.

What is a PDU?

In server rooms and communications fields, a PDU, short for Power Distribution Unit, is commonly referred to as a "rack-mounted power strip." Through industrial-standard PDUs, network product power safety is improved, and they meet the power input requirements of critical equipment. The power socket is the last barrier before devices draw electricity; if it is unstable and lacks sufficient protection, it may damage expensive equipment or cause system failures. Thus, the safety and stability of power sockets are crucial for the value of the equipment in the data center and the entire system.

For data centers, there are two primary types of PDUs to choose from based on installation methods:

· Horizontal PDU (mounted horizontally): Typically occupies 1U to 2U of rack space and is installed on rails in 19-inch or 24-inch racks.

· Vertical PDU (mounted vertically): This type is more commonly seen today, provides more sockets, and is mounted on the back of the rack to continuously supply power to the devices.

Main Types of PDUs in Server Rooms

Basic PDU:
Basic PDUs are simple power strips. However, compared to regular sockets, they offer higher safety, reliability, continuity, and stability.
( Image source: Baidu Network Images)

Metered PDU:
Metered PDUs provide real-time remote monitoring for each socket and allow remote on/off control for individual outlets. Simply put, once devices are connected to the PDU, you can remotely control them through a browser or software, providing precise management of power supply, including the ability to restart or shut down switches and servers.

Key Considerations When Choosing a PDU:

The number of sockets on a vertical PDU depends on its length, which in turn is determined by the height of the server rack. A basic vertical PDU typically has at least 40 sockets, arranged alternately. Some PDUs separate circuits into multiple branches, each with its own fuse or breaker. Alternating phase PDUs distribute power to each socket. Choose the number of sockets based on the rack configuration; most server outlets use C13/C14 sockets, with larger devices using C19/C20 sockets.

Traditional PDUs categorize output sockets by branches, and as rack density increases, cable management and load balancing become significant challenges. If the load is not properly balanced, data center managers may face risks such as circuit overload or power outages. Color-coded output sockets can help IT personnel more easily identify circuit configurations, simplifying the deployment process and reducing the risk of overloading the power supply.

PDU Usage Considerations

Since vertical PDUs are installed at the back of racks, they are exposed to the heat released by IT equipment. PDUs with a higher temperature rating can reduce the risk of failure. Many PDUs have optional temperature and humidity sensors to avoid the impact of hot air, and normal operating temperature ranges from -5°C to 60°C. Maintenance personnel can make adjustments based on specific conditions.

Metered PDUs can provide visual data such as voltage, current, and power. These PDUs reduce the risk of overload and help data center operators optimize space utilization and energy efficiency. Input metered PDUs can monitor circuit breakers and phases in real-time, while output metered PDUs can track the power load on the output sockets. Network-connected PDUs allow IT staff to view real-time data remotely.

Key Considerations When Choosing Intelligent PDUs

Smart (metered) PDUs enable precise monitoring and control of energy consumption. They provide data center operators with information to streamline power infrastructure and eliminate unnecessary costs. The other important considerations when choosing smart PDUs are reliability, functionality, and adaptability.

1.Reliability:
Smart PDUs should not compromise their core functions when integrating advanced features. It's essential to buy PDUs from manufacturers who thoroughly test each unit, ensuring the reliability of core functions throughout product development.

2.High Temperature Rating:
As companies increase efficiency, data centers tend to raise thermostat temperatures to reduce energy consumption, which can lead to higher ambient temperatures. This requires PDUs designed to operate at higher temperatures. The maximum working temperature of PDUs ranges from 45°C to 60°C, and high-temperature rated PDUs are needed for environments where the temperature is higher than usual.

3.Alternating Sockets:
As rack density increases, cable management and load balancing become challenges. If the load across circuits and phases is not properly balanced, managers may face overloads or outages. To simplify circuit/phase balancing and cable management, many PDU manufacturers provide color-coded alternating sockets, which significantly simplify deployment.

4.Locking Sockets:
A locking mechanism on sockets ensures that the physical connection between IT equipment and the PDU remains intact, preventing accidental disconnections that could cause load fluctuations. The most commonly used socket standards worldwide are IEC320 C13 and C19, which are internationally compatible and can support up to 43.5KW of power. There are various socket options available, ranging from anti-pull sockets to lockable sockets.

5.Functionality:
Smart PDUs can measure, manage, and report the energy usage of data center equipment in real time. With precise energy metering and control, data center managers can optimize energy usage and more easily support changes in equipment and capacity. Once energy consumption data is known, there is a stronger case for investing in more advanced technologies.

Data center managers can use smart PDUs to remotely schedule power cycling for unused IT devices, reducing energy consumption. They can streamline power infrastructure to eliminate unnecessary capital expenditures, allocate costs based on actual energy consumption, and proactively manage energy use to increase efficiency.

Adaptability:
Rack-level flexibility is key to adapting to ever-changing business needs. Smart PDUs are designed to replace large, inefficient infrastructure systems with more efficient solutions that save both energy and cost. Data center managers can easily update their monitoring modules to new technologies without replacing the entire power panel or interrupting critical server power.