Originally posted to Future-tech,
In the UK and Europe the standard LV system is 400/230V TN-S. The transformers needed to convert from the HV system (11kV in the UK) to LV should result in a standard LV system of this type. The designation TN-S describes the fact that the LV system neutral is separate from the earth system throughout the installation, with one neutral-earth connection at the transformer. There are various other configurations – TN-C-S, IT,TT etc but these are not suitable for data centres for various reasons, this is the subject of a separate blog.
The overriding concern for the designer is safety – life safety for personnel in the facility and the safety of the critical IT equipment. These are intimately linked. The danger to life of direct contact with the HV is prevented by insulation and secure containment and can be considered the easy part of the design. The difficult part is fault protection – ensuring that an earth fault on the HV system does not result in a voltage rise on the LV system that is dangerous to life or property.
To read the cull article please click here.