We were there

The German company Datacenter One GmbH operates data centers in Stuttgart, Leverkusen, and Hilden in Germany. In addition, the company designs and builds turnkey data centers within six to nine months, starting at 500 m² of data center space—including custom-built facilities at customer locations.

The operator also offers colocation services. Customers receive a dedicated, enclosed space within the data center where they can install their own equipment. This allows them to leverage the existing infrastructure while scaling capacity as needed—without interrupting operations. Service levels—such as high availability and voltage and frequency tolerances—are defined in Service Level Agreements (SLAs).

At the Hilden site, Project Manager Christian Werner is responsible for ensuring compliance with these standards. He is well aware of the specific requirements of the colocation business: “In our SLAs, we guarantee a defined level of power quality within specified tolerance limits. If we fail to meet those requirements, customers can hold us accountable.”

To ensure reliable operations, Christian Werner trusts on Janitza measurement technology. These systems primarily monitor the backbone of the power distribution system: two independent power paths. To ensure accurate tracking of high availability, energy management, and cost allocation, Janitza devices monitor all critical points across the facility. Gerald Fritzen, data center specialist at Janitza, explains the concept: “We implemented a comprehensive monitoring system, starting with primary and secondary power sources such as transformers and generators. This extends all the way down to the secondary distribution units supplying the server racks.”

The metering technology also complies with the strict thresholds required for uninterruptible power supply (UPS) systems. Residual current monitoring is a critical safety function in data centers. These are currents that do not remain within the intended circuit but flow through unintended paths. Residual currents indicate insulation faults that can lead to system disruptions. Monitoring is also performed using Janitza devices, and in the Hilden facility, values remain consistently within optimal ranges.

The leased customer areas also have their own power supply. These are continuously monitored as well, using cost-efficient entry-level devices. “Thanks to the 20 channels available in these devices, we can monitor both residual currents and operating currents across all outgoing feeders—and still have capacity for future expansion,” says Gerald Fritzen. This includes local alarm functions: high-visibility warning lights above the control cabinets provide visual alerts—orange indicators signal when residual currents exceed defined thresholds.