Transformers & Substations

The transformer is usually the longest lead item in an electrical package and the least forgiving to change late, which is why it deserves attention at the start of procurement rather than the end.

The first decision is dry type against oil immersed. Dry type and cast resin units suit indoor locations, basements and buildings where fire load and oil containment are a concern, and they need adequate ventilation because their cooling depends on it. Oil immersed units are generally more efficient for a given rating and handle overload better, but need containment, fire separation and maintenance access, which usually puts them outdoors or in a dedicated substation room.

Sizing goes beyond the connected load. Growth allowance, the effect of harmonic loading from drives and IT equipment, and the real ambient temperature all shift the answer. A transformer loaded near capacity in a hot room ages faster than the datasheet life, and that ages quietly until it fails.

Losses matter more than most buyers expect. No load losses run every hour of every year, so a slightly more efficient unit often pays back its price difference over the installation's life, particularly on a facility that never switches off.

Package substations bring transformer, MV switchgear and LV distribution into one factory built assembly, which cuts site work and coordination risk. Ring main units handle the MV ring in distribution networks.

NLS Power supplies dry type, cast resin and oil immersed transformers, package and unit substations, ring main units, auto transformers and transformer protection relays.