Large loads such as production lines, control rooms and data rooms need a three-phase UPS. The principles are the same as for a small unit, but the choices are bigger: they involve cost, space, power quality and reliability, and the cost of failure is also bigger.
Key takeaways
- A three-phase UPS is rated in kVA and kW; read the kW, which is the real load capacity.
- It may take three-phase input and give three-phase output, or give single-phase output.
- Decide on bypass, redundancy and battery runtime from the cost of downtime.
- Check input power quality, harmonics and compatibility with a generator.
1. Input and output
Most industrial UPS units have three-phase input and three-phase output, for three-phase loads and balanced operation. Some give single-phase output from three-phase input. Choose to match the loads and the supply; see single-phase vs three-phase.
2. Sizing
Add up the loads in kW, include growth and a margin, and read the UPS rating in kW at the power factor and conditions stated by the maker. Motors and similar loads have a surge; if you need them on the UPS, the sizing must say so. See how to size a UPS.
3. Bypass and maintenance
A static bypass transfers the load to the mains if the UPS has an overload or fault. A maintenance bypass lets you take the UPS out for service without cutting power to the load. Insist on both for critical loads.
4. Batteries and runtime
Large UPS units use battery cabinets or racks. The runtime may be a few minutes, enough to start a generator, or longer where there is none. Cabinets, ventilation, fire safety and battery monitoring all matter; see battery safety.
5. Power quality and generators
A large UPS draws current from the mains in a particular way, with some distortion called harmonics. A UPS with a clean input reduces the effect on the supply and on a generator. Check that the generator is sized for the UPS plus its battery charging, and that the two work together.
6. Examples of ranges
Typical choices include scalable units such as the Eaton 93PM, large monolithic units such as the Socomec DELPHYS MX, and modular systems such as the Socomec MODULYS GP. See also UPS bypass, redundancy and modular systems.
Next step
For a plant or data room, we survey the loads and the supply, then propose the UPS and battery system. Ask through the quotation form or see our industrial UPS solutions.
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