How Energy Monitoring and Smart PDUs Contribute to More Efficient Data Centres

Data centres are becoming increasingly sophisticated, with applications like AI, HPC, and edge computing demanding robust infrastructure. Simultaneously, the need for transparent energy distribution, monitoring, and optimisation is growing. This article explores how smart PDUs and inline meters—such as those from Schleifenbauer—enhance energy management in server racks and entire data centres.

What Is a PDU and Why Is It Crucial in a Data Centre?

A Power Distribution Unit (PDU) is essential for distributing power within a data centre. They supply power to servers, switches, and other equipment housed in racks. Modern PDUs offer more than just power distribution. There are several types of PDUs:

• Basic PDU: Simple power distribution without monitoring.

• Metered PDU: Displays energy consumption per input or per circuit (branch).

• Monitored PDU: Measures energy consumption per outlet.

• Switched PDU: Provides remotely switchable outlets.

• Managed PDU: Combines outlet monitoring and switching with network management (e.g., via SNMP or Modbus).

Why are PDUs important? They offer insights into energy consumption, help prevent peak loads, and enable remote management—crucial for unmanned locations or scalable infrastructures.

What Is an Inline Meter?

An inline meter is a compact energy meter placed between an existing power supply, for example, in or before a server rack. These meters measure:

• Voltage (Volts)

• Current (Amperes)

• Energy consumption (kWh)

• Power factor

• Frequency

Inline meters are a smart solution for data centres that do not use monitored PDUs but still require energy insights per rack.

What Is the Difference Between a Metered and a Switched PDU?

• A metered PDU only measures and does not offer remote switching capabilities.

• A switched PDU allows for remote switching of outlets and often includes measurement functionality.

At Schleifenbauer, switched PDUs are equipped with:

• Bistable relays (for low energy consumption)

• Near Zero Voltage Switching (safe switching)

• Switching delay (to limit inrush currents)

How Do You Measure Energy Consumption Per Rack?

For rack-level energy measurement, there are three common methods:

1. Using monitored PDUs (input, branch, or outlet measurement)

2. Placing inline meters between the power supply and rack equipment

3. Applying external energy meters in the distribution panels

The choice depends on your infrastructure and scale. Managed PDUs and inline meters from Schleifenbauer support protocols such as MODBUS/TCP, SNMP v3, REST API, and Snoobi Analytics.

How Do You Improve the PUE of a Data Centre?

Power Usage Effectiveness (PUE) indicates the ratio between the total energy consumption of a data centre and the consumption of the IT load. The closer to 1.0, the more efficient.

Smart PDUs and inline meters help improve PUE by:

• Providing real-time insights into energy consumption per rack

• Detecting inefficient equipment (“zombie servers”)

• Optimising load per circuit

• Integrating with DCIM and monitoring tools

How Much Power Does a DGX H100 Server Consume?

An NVIDIA DGX H100 system consumes an average of 10–12 kW per node. For a rack with multiple DGX systems, a robust PDU is required:

• 3-phase 63A PDU

• Combi-outlets (e.g., C13/C15/C19/C21 via Scolmore CX)

• Monitoring per outlet

• Surge protection and residual current detection

Schleifenbauer offers these high-density PDUs in various variants (Basic, Metered, Monitored, Switched, Managed).

Protection Against Surges and Residual Current

A modern PDU must do more than measure and switch. Protection against risks is equally important:

• Surge protection type 1, 2, or 3

• Residual Current Monitoring (RCM) for leakage currents

• Industrial fuses and temperature sensors

At Schleifenbauer, these functions can be optionally integrated, depending on usage and risk analysis per data centre.

Frequently Asked Questions About PDUs and Inline Measurement

What is a PDU in a data centre?

A PDU (Power Distribution Unit) distributes electrical power to equipment in a server rack and can be equipped with measurement and switching technology.

What is the difference between metered and monitored PDUs?

Metered PDUs measure per input or circuit, while monitored PDUs also measure per outlet.

What is an inline meter?

A compact energy meter placed between the power supply and equipment to measure