Server Rack Power Supply and UPS
How IT keeps running when the mains fail
A reliable server rack power supply is the base for everything else in the cabinet. A short power cut or a voltage dip can crash servers, corrupt data and take a network offline, often at the worst moment.
An uninterruptible power supply (UPS) bridges power failures and gives systems time to shut down cleanly or keeps them running until the mains return. Power distribution units (PDUs) bring the power to each device in the rack, and monitoring shows load and faults before they cause trouble.
Lehmann IT plans UPS and power distribution together with the cabinet, so space, cooling and cabling fit from the start. The question below explains how a UPS protects your IT.
Questions on power supply
Find the products in the Lehmann IT shop
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Accessories: PDUs and UPS →Server cabinets →Advisor: UPS Systems
The most common questions, answered briefly by Lehmann IT.
Why a UPS?
It supplies power without interruption, protects against voltage spikes and, in the event of a power failure, gives you time to keep working and save your data.
Single-phase or three-phase?
The single-phase CONVERT covers 1 to 6 kVA. The WISUS-K and the WP Series Type T work in single- and three-phase, and all other series are three-phase, up to several MVA.
What does a modular UPS offer?
Power modules can be added when demand grows and planned in for redundancy (n+1). In several series the modules are hot-swappable.
Does the UPS fit in the server cabinet?
The CONVERT, the WISUS-K and the WISUS-G are available as floor-standing units or for the 19-inch rack, while the WP Series Type R is designed for installation in existing rack cabinets.
Which UPS fits?
Choose by power and design, one click takes you straight to the product.
Single-phase, 1 to 6 kVAMonoblock, rack or floor-standingCONVERT I & II →Single- and three-phase, 6 to 20 kVAMonoblock, rack or floor-standingWISUS-K →Single- and three-phase, 10 to 120 kVAMonoblock, tower with batteriesWP Series Type T →Three-phase, 25 to 125 kVAModular, all-in-one possibleWISUS-MC →Three-phase, from 50 kVAModular, up to 97 % efficiencyWISUS-MS →UPS systems at a glance
The key features. Hover over a card.
Power1 kVA to MVA
Phasessingle- and three-phase
DesignMonoblock · modular
InstallationFloor-standing or rack
Redundancyn+1
AccessoriesBypass · Network · Battery
PDUs and power strips
Distributing and measuring power in the rack: PDUs for server cabinets and data centers.
Power strip for UPS
Distributes the output of the UPS in the rack: 19-inch power strip for UPS systems.
Rack Monitoring
Monitoring temperature, humidity and access in the cabinet: Rack monitoring systems.
The right server cabinet
For servers, UPS modules and batteries: Server and network cabinets from Salach, Germany.
UPS systems at Lehmann IT: All UPS systems · CONVERT I & II · WISUS-K · WISUS-G · WP Series Type T · WISUS-MC · UPS accessories
How to plan the power supply
- Add up the load: list every device in the rack with its power draw, so the UPS and the power distribution can be sized correctly.
- Decide on the bridging time: a few minutes for a clean shutdown, or longer runtime to keep systems online through longer outages.
- Plan redundancy: critical systems with two power supplies should be fed from two separate circuits or PDUs.
- Keep space and heat in mind: a UPS takes height units and produces heat, so it belongs in the cooling and space plan from the start.
- Add monitoring: metered or switched PDUs and UPS management show load, faults and battery condition before problems arise.
Frequently asked questions
What does a UPS do in a server rack?
An uninterruptible power supply sits between the mains and the IT equipment. When the mains fail or the voltage drops, its batteries take over without interruption. This keeps servers running long enough to shut down cleanly or to bridge the outage until the power returns.
How long should a UPS bridge a power failure?
That depends on the goal. For a controlled shutdown, a few minutes are usually enough. If systems must stay online through longer outages, the UPS needs more battery capacity or must hand over to a generator. The load in the rack determines how much capacity is needed.
What is a PDU?
A power distribution unit is the socket strip of the server rack. It distributes power to the individual devices and comes in versions from simple strips to metered and switched units that show the current load and allow sockets to be switched remotely.
Does a UPS belong in the rack or in a separate room?
Smaller UPS units for a single rack usually sit inside the rack. Larger systems that supply many racks often stand in a separate room. In both cases, weight, heat and access for battery replacement have to be planned.
How do I know the batteries still work?
UPS management software reports battery condition, runtime and faults, and runs regular self-tests. Batteries age over time, so a planned replacement before they fail is part of reliable power protection.
What happens when the UPS battery runs low?
A managed UPS warns the connected systems before the battery is empty. Shutdown software then closes applications and switches servers off in the right order, so no data is lost even during a long outage.
Can power and cooling be planned together?
They should be. Every watt that goes into the rack comes out as heat, so the power plan and the cooling plan depend on each other. Lehmann IT plans cabinet, power distribution, UPS and cooling as one system.
Planning with Lehmann IT
Lehmann IT has designed and built server cabinets in its own production in Salach, Germany, since 1983. Because development and manufacturing sit under one roof, standard cabinets can be adapted and special versions built when a project needs them. This knowledge site explains the technology in depth, so you can understand the options before you decide. When you know what you need, the Lehmann IT shop at lehmann-it.de shows the matching products with prices and configuration options, and the team in Salach helps with questions on power supply by phone or email.