S20-35KV Oil-Immersed Electrical Transformer
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Start with the electrical duty
A useful enquiry begins with rated capacity, primary and secondary voltage, frequency, phase, vector group, impedance, tap range and the expected load profile. Projects may refer to common African distribution classes such as 11 kV, 22 kV, 33 kV or 35 kV, but the offered voltage and capacity range must be confirmed for the selected model. Please also identify motor loads, harmonic loads, renewable generation or frequent overload conditions that could affect the design review.
Choose the tank and cooling arrangement
The correct construction depends on maintenance practice, installation space and operating conditions. A sealed tank can reduce routine oil handling, while a conservator arrangement may be requested for other operating or maintenance preferences. Cooling design, oil type, radiator arrangement and temperature-rise limits should be specified together. If forced-air cooling or another special arrangement is required, include it in the enquiry so engineering can confirm availability and documentation.
Evaluate losses over the operating life
Purchase price is only one part of transformer cost. No-load loss, load loss, efficiency at the expected loading level and local energy cost can materially affect lifecycle value. Send the loss limits from the utility specification or tender instead of relying on a generic “low-loss” label. LONTEN can then review whether a documented configuration is available and identify any trade-off involving conductor material, temperature rise, dimensions or lead time.
Prepare for heat, dust, altitude and corrosion
African utility, mining and industrial sites can combine high ambient temperature, dust, humidity, coastal corrosion or elevation. These conditions should be declared before selection because they may influence temperature rise, insulation coordination, enclosure finish, bushings and cooling margin. Provide maximum and minimum ambient temperature, altitude, installation location and any corrosion category or coating requirement. Site data is more useful than a broad claim that one transformer is suitable for every climate.
Define accessories and protection
The accessory schedule may include temperature indicators, pressure-relief devices, oil-level indication, drain and sampling valves, marshalling arrangements, cable boxes, surge-protection interfaces or other utility-specific items. Bushing type, terminal orientation and cable-entry details should be shown on the drawing. List mandatory accessories in the RFQ so the quotation, drawing and inspection plan describe the same scope.
Agree the test and document package
Before order placement, identify the required routine, type and special tests, witness points, drawing approvals, inspection plan, nameplate language and final documentation. If a tender cites IEC 60076 or a local utility specification, provide the exact edition and required test schedule. Compliance should be stated only after the responsible team confirms that the selected model and report set cover those requirements.
Send a complete transformer RFQ
For a useful technical and commercial review, send the required kVA, voltage ratio, frequency, phase, vector group, impedance, tap range, loss limits, cooling method, ambient conditions, altitude, accessories, test schedule, quantity and destination. LONTEN will use these inputs to identify the next questions and prepare a configuration for review. Final performance and compliance statements remain subject to approved drawings and model-specific documents.