Industries
Data centre transformers and power equipment, from the grid connection to the rack
Transformers and switchgear, standby generators, UPS, busway, cooling and fiber, specified in the order the power flows. Your redundancy concept sets the ratings, and the long lead items set the programme.
The equipment chain
- 01GridThe connection offer comes first. Its capacity caps the IT load the site can ever carry, and its energisation date usually sets the programme.
- 02MV switchgearTakes the incoming feeders and switches each transformer. Where the site has two grid feeds, a bus coupler lets either one carry the whole site.
- 03TransformerSized on the load one path carries alone, not on the site total. Dry type units inside the building keep insulating liquid out of the data hall.
- 04Transfer switchWhere the standby generator joins the chain. It moves the board to the generator when the grid fails and back when it returns, while the UPS carries the IT load through the break.
- 05UPSCarries the IT load through the seconds between a grid failure and the generator taking over. Modules are sized per path, N+1 or 2N.
- 06Busbar trunkingRuns overhead along the rows with a tap off unit at each rack position, so a new rack is connected without a new cable back to the board.
- 07Rack PDUThe last step: it feeds the servers through C13 and C19 outlets, often with metering per outlet so each rack's draw is known.
A data centre buys one chain, and it starts at the grid. The connection capacity and the date it is available decide what can be built and when. So the grid side comes first: medium voltage switchgear, transformers and, where transformation sits outside the building, a compact substation.
Redundancy decides the sizing. In a 2N design each of the two paths, transformer and board, carries the full IT and cooling load alone while its partner is out of service. In N+1 there is one unit more than the load needs: each is sized for the load divided by N, and the remaining units carry the whole load when one fails.
Behind the grid side sit the standby generators that carry the load when the grid fails, and the UPS, busway and rack PDUs that carry it to the IT equipment. Cooling removes the heat that load becomes, and its redundancy follows the same concept.
The other constraint is time. Transformers and medium voltage switchgear are long lead items, and your programme usually needs them before the building is complete. Ordering early on a frozen specification is often worth more than a slightly better price later.
What decides the ratings
The non redundant load, the full IT and cooling demand that one path carries alone, sets the transformer and board ratings. The level of redundancy is a design and contract decision, commonly expressed through availability classes such as those in the EN 50600 series.
Uninterruptible power supplies and other converter loads produce harmonic currents. The transformer vector group affects how those currents pass to the medium voltage side, and your designer's harmonic assessment fixes the transformer specification.
A standby set is rated for a duty, standby or prime, and picks up the UPS systems and chillers in steps. The largest single step, not the total, often sets its alternator and governor response.
What to settle early
| Consideration | Why it matters here |
|---|---|
| Redundancy concept | 2N: each path carries the full load alone. N+1: each unit carries the load divided by N |
| Dry type or liquid immersed | Dry type units inside the building simplify the fire strategy |
| Harmonic loading | Converter loads affect transformer specification and losses |
| Fault level | Parallel or closely coupled transformers raise the fault level the boards must withstand |
| Lead time | Transformers and medium voltage switchgear usually set the critical path |
| Flexible connection terms | A network operator may offer a connection with a power limit rather than a firm connection |
| Standby generation | The duty rating, the largest load step and the runtime on the fuel stored at site |
| UPS and cooling | Redundancy per system, the rack density and the cooling medium |
The German example
In Germany, the Energy Efficiency Act covers data centres from 300 kW of non redundant rated connection power and sets efficiency requirements by the date operation begins.
Equipment for this application
What we need to quote
- The redundancy concept and the non redundant load per path
- Transformer ratings, voltages and whether they are indoor dry type units
- Medium voltage panel schedule and the network connection data
- Low voltage board ratings and the prospective fault level
- Harmonic assessment or the UPS and converter loads
- For standby generation: the duty, the largest load step and the runtime
- For UPS and cooling: the redundancy per system, the rack density and the cooling medium
- The programme date the equipment has to be on site
Building or expanding a facility?
Send the whole equipment schedule as one project, each item with its own requirements.