CAST RESIN TRANSFORMERS
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Cast Resin Transformers Reliable. Proven. Simply fact.

Why cast resin transformers made by SGB-SMIT? The range of SGB-SMIT cast resin transformers includes power ratings up to 25 MVA and rated insulation voltages up to 36 kV as well as converter, distribution and special transformers. With its over 30 years of experience in the construction of cast resin transformers, SGB-SMIT‘s scope of special expertise is one of the largest world-wide, a fact which is reflected by the extremely high quality level such as our MTBF (mean time between failures) of over 2,400 years. Thanks to their special design, SGB-SMIT cast resin transformers offer a range...

High voltage winding The high voltage winding (HV winding) is the heart of the cast resin transformer. It embodies the enormous technical know-how of SGB-SMIT. Thermal reserves due to special primary insulation allow for overload. Cooling ducts ensure long service life. Double-layer winding enables the handling of high surge voltages. Cast resin transformers are characterized by the conductors of the HV winding being embedded completely in an enclosed cast resin body with a smooth surface. Even if not specified so explicitly by the standard, this can be achieved in production of high...

R|eserves-equipped Thermal reserves allow for overload In this regard, SGB-SMIT cast resin transformers are not only one step ahead of oil transformers, but also of cast resin transformers made according to conventional technology. These use a continuously wound coil whose conductor consists of an aluminium coil and the winding/layer insulation of foil. The insulation corresponds only to insulation class F and even this qualification is only reached in conjunction with the entire insulation system - without thermal reserves. This is completely different in the case of SGB-SMIT cast resin...

S|urge-proof Reliable handling of high surge voltages Only SGB-SMIT cast resin transformers feature vacuum-encapsulated high voltage coils whose winding is designed as a double-layer winding. This means safety in the handling of surge voltages as are caused by lightning strikes or by vacuum circuit-breakers. • The continuous coil winding of other transformers results in a strongly fluctuating voltage stress, especially of the input windings, as 70% of the surge voltage stress is taken up by the first 30% of the windings. Thus, the risk of short-circuited coils increases considerably for...

Low voltage winding The low voltage winding of SGB-SMIT cast resin transformers is almost always designed as coil-winding. The benefits of this winding design are self-explanatory: • Reduction of extra losses • Balanced temperature distribution within the winding • High short-circuit capability Exceptions exist, for technical reasons, only in case of minor ratings below 250 kVA and for higher system voltages (> 3.6 kV). For over 40 years, SGB-SMIT has manufactured coil windings for distribution transformers and cast resin transformers. This long-standing experience is the reason for...

The core For specifying cores for cast resin transformers, no-load losses, noise and no-load current are essential quality features which are, in many cases, of decisive importance. Thus, the core design is an important engineering task. This includes the precise geometrical design, determination of the material properties of the magnetic sheet to be used and many details, including design measures such as those to control vibrations, slanting positions and other mechanical requirements. Core lamination with high-temperature resistant varnish is suitable for all – even extreme –...

Cast resin transformer – key components Upper yoke Low voltage terminal lug Connection of temperature sensors High voltage winding Lower steel clamps

Upper steel clamps Jack rings Support blocks High voltage terminal lugs Delta connection Casters Lower yoke

Reliable. Proven. Simply fact. With production starting in the late 1970‘s, SGB-SMIT were one of the first manufacturers of cast resin transformers, thus we are able to offer our customers the benefit of our extensive experience and know how. This extraordinary know-how is reflected by a especially high quality score, e.g. an MTBF of over 2,400 years. It goes without saying that SGB-SMIT cast resin transformers meet all the established quality conditions: Fire classification F1 • Environmental class E2 • Climate classification C2 And as a matter of course, the product sector Cast-Resin...

Reliable. Proven. Simply fact. Special feature: internal test equipment – a cutting-edge test laboratory SGB-SMIT cast resin transformers are designed and manufactured as standard in accordance with IEC 60076-11. In line with the value-added chain at SGB-SMIT, all routine and type tests specified in this standard and the most important special tests are performed in our own, modern test area. Thus, the special characteristics stipulated in the customer‘s specification can also be verified. 1 • Routine tests: Fig. 1 · Measurement of the winding resistance · Measurement of the transformer...

Installation conditions Installation conditions SGB-SMIT cast resin transformers make minimum demands on the site of installation. This results from the above-mentioned regulations regarding groundwater protection, fire protection, functional integrity in DIN VDE 0101, DIN VDE 0108 and ELT Bau VO (Body of regulations for the building trade). With SGB-SMIT cast resin transformers, no measures are required for water protection. If however, the cast resin transformer with a rated voltage of over 1 kV is to be used for facilities accommodating crowds of people according to DIN VDE 0108 and ELT...

Reliable. Proven. Simply fact. Efficiency Transformers are capital goods with a service life of many decades; thus, the purchaser should not only focus on the comparison of acquisition prices, but also and especially of the presumable maintenance costs and those resulting from no-load losses (iron core) and load losses (windings). SGB-SMIT offers different loss variants from normal to highly reduced values. Basic diagram “Own consumption“ as a function of the load Higher acquisition costs due to higher outlay for laminations and winding materials coincide with lower operating costs. It is...