Triangular Wound Core Oil-Immersed Transformer

Not on the electricity bill. No-load and load loss of the S13-M·L are cell for cell the same as the S13 of that rating — 570 W and 6200 W at 630 kVA — so the annual energy cost calculated from loss comes out the same. What it lowers is no-load current: 1.1% down to 0.15% at 630 kVA. What that buys is less reactive power at no load, a smaller inrush on energising and lower magnetising harmonics, not kilowatt-hours. To save money on loss, compare loss generations or an amorphous core instead.

Three things. Less magnetising reactive power drawn at no load, which adds up across a distribution network of scattered substations at low load factor and eases the reactive burden on the lines and the transformer upstream. A lower inrush multiple on energising, which is easier on upstream protection settings and on installations switched frequently. And a magnetising current rich in third harmonic by nature: a smaller current injects less of it, which helps sensitive loads on the same busbar.

Start from the capacity. S13-M·L stops at 1600 kVA, and 2000 and 2500 kVA exist only as S11-M·L. At 1600 kVA and below, the S13-M·L is one step lower in no-load loss (570 W against 810 W at 630 kVA) and lower in no-load current as well (0.15% against 0.20%), while load loss is the same for both. Where the no-load figures matter, take the S13-M·L.

The projected outline differs from a conventional rectangle, so foundation and fence are set out from the actual shape and the foundation drawing of a rectangular unit of the same rating cannot simply be reused. At 630 kVA the overall dimensions are 1395×1210×1649 mm, total weight 2085 kg, mounting dimensions E1 550 mm and E2 820 mm. Inside a package substation or a prefabricated module, check the clear height of the transformer room, the maintenance aisle and the cooling air path against the hexagonal outline, particularly the diagonal dimension. Before an in-place replacement, measure the wheel gauge and the usable ground outline of the old foundation.

The construction favours it. At a lamination joint the flux lines have to cross the gap between laminations, and that is one of the concentrated sources of magnetostrictive noise; a continuously wound magnetic circuit has no such joints, and with the three flux paths symmetrical as well the noise of the unit itself is lower than a stacked construction of the same rating. The specific sound level follows the capacity chosen, and the level actually reaching the site boundary or a sensitive receiver also depends on installation position, ambient acoustics and distance attenuation, and is calculated per project.

Yes. Where it travels with the module, the prefabricated power module line takes on the enclosure, the internal arrangement and the foundation fixing, and the transformer leaves the works as equipment inside it. An oil-immersed unit inside a module needs an oil pit or oil-retention arrangement sized on the oil volume; the hexagonal outline has a noticeable effect on the clear space of the transformer room and on how the aisles are laid out, so it is settled in one pass from the actual outline at the layout drawing stage.