UPS system design

An uninterruptible power supply keeps critical equipment running through power dips, outages and the seconds before a generator takes over. We design UPS systems for server rooms, data centres, healthcare and laboratory equipment, building controls and security systems, sized for the real load, arranged so they can be maintained and coordinated with the rest of the building's electrical system.

Many UPS problems are not equipment failures. They are design gaps: a unit with no way to bypass it for maintenance, batteries that give a fraction of the expected runtime, a generator that will not accept the UPS as a load, or a single unit protecting equipment that the business assumed was redundant. We start by asking what the UPS is protecting and what would happen if it failed.

What we design and build

• UPS sizing from measured or estimated loads, with allowance for growth and the equipment's power factor.
• Topology selection: standby, line-interactive or online double-conversion, matched to how sensitive the load is.
• Battery selection and runtime, including valve-regulated lead-acid and lithium-ion options, battery cabinets or rooms, ventilation and spill or thermal requirements.
• Redundancy arrangements: single units, parallel modules with a spare, and dual independent paths for dual-corded equipment.
• Static and maintenance bypass arrangements, so the UPS can be serviced without shutting down the load.
• Input and output distribution: feeders, panels, rack power distribution and transfer equipment.
• Coordination with standby generators, including transfer timing and generator sizing for UPS loads.
• Monitoring, alarms and automated shutdown, connected to building automation or network management where useful.

Every design starts from the same basic arrangement, shown below. Normal power is converted to DC, which keeps the batteries charged and feeds an inverter that rebuilds clean AC for the load. Two bypass paths let power reach the load when the UPS itself cannot, or must not, carry it.

How it works

1. We start with why. What equipment needs protection, what an interruption would cost, how long the load must ride through, and whether a generator exists or is planned. These answers decide topology, runtime and redundancy.
2. Load and site review. We review existing loads from panel schedules, metering or equipment data, inspect the electrical room, the space for the UPS and batteries, ventilation and cooling, and the existing distribution and generator.
3. Options and concept. We present one or more arrangements with their trade-offs in reliability, maintainability, space, heat and cost, so you can choose with the facts in front of you.
4. Detailed design. Single-line diagrams, equipment and battery specifications, bypass and distribution arrangements, room layout, ventilation and cooling requirements, protective device coordination and monitoring points. Drawings for permit are sealed by a licensed professional engineer where required.
5. Construction support. Installation is done by licensed electrical contractors under permit. We review submittals and shop drawings and visit site to check the work.
6. Commissioning. We help plan and witness start-up and testing by the manufacturer's service technicians: transfer to battery, transfer to bypass and back, generator operation with the UPS loaded, and alarm and shutdown signals.

What to have ready

• A list of the equipment to be protected, with nameplate or measured power where available.
• The runtime the business needs, and whether a generator will carry the load after the batteries.
• Electrical drawings and panel schedules for the area, and generator details if there is one.
• Any existing UPS documentation, battery age and recent service reports.
• Plans for growth over the life of the equipment.

Redundancy: matching the design to the risk

A single UPS protects against utility problems, but not against a failure of the UPS itself. Redundant arrangements add capacity or whole paths so one failure does not drop the load. The right level depends on what an outage costs you, whether the equipment has one power cord or two, and how often you need to maintain the system without a shutdown.

What you get

A design package your contractor can price and build: single-line diagrams, equipment and battery specifications with runtime calculations, layouts for the UPS, battery and distribution equipment, ventilation and cooling requirements, and a sequence of operation describing what happens on power failure, generator start, return of utility power and transfer to bypass. It includes a commissioning test plan and, at the end, record documents and a summary of the maintenance the system will need.

For existing systems, we can also provide a condition and risk review: how the UPS is loaded, the age and condition of the batteries, whether it can be maintained without an outage, and what single points of failure remain.

Who it's for

• Owners and IT managers with server rooms, network rooms or small data centres.
• Healthcare, laboratory and research facilities with equipment that cannot tolerate interruption.
• Facility managers protecting building automation, security, access control and communications systems.
• Industrial sites with process controls and instrumentation.
• Anyone replacing an ageing UPS or adding a generator to a building that already has one.

For background, read UPS topologies, UPS batteries and runtime, UPS bypass and maintenance and data centre redundancy: N, N+1 and 2N.

Common questions