A 35KV power transformer is a medium-voltage transformer designed to transfer electrical energy between a high-voltage distribution system and a lower-voltage network used by industrial plants, utilities, renewable-energy facilities, and infrastructure projects. In practice, buyers should confirm whether the project requires a 35kV nominal system or equipment with a 36kV maximum system voltage rating. At Liye, we help customers select the transformer by matching voltage, capacity, insulation, cooling, installation environment, protection requirements, and applicable technical standards.
Please visit our website for more information on this topic.
The correct model is not selected by voltage alone. A complete specification normally includes rated power in kVA or MVA, high- and low-voltage ratings, frequency, vector group, impedance, tap range, cooling method, insulation level, enclosure arrangement, and site conditions. This guide explains the main options and gives a practical procurement framework for buyers comparing 35KV power transformer suppliers.
A 35KV power transformer is a static electrical device that uses electromagnetic induction to change voltage while maintaining the same power frequency. A common application is stepping down power from a 35kV distribution feeder to a usable medium- or low-voltage level for factories, commercial facilities, substations, or utility networks. The transformer does not generate electricity; it provides voltage conversion and electrical isolation within the power distribution system.
The transformer reduces transmission or distribution voltage to a level suitable for downstream equipment, while its insulation system separates the primary and secondary windings electrically. It also supports system coordination through its impedance, vector group, grounding arrangement, and tap changer configuration. When properly specified, it can help maintain stable voltage and limit the effect of short-circuit currents, although the final protection design must be completed by the project engineer.
Exact ratings depend on the project and local grid requirements. Many 35kV systems use equipment in the 36kV insulation class, but this should never be assumed without reviewing the utility specification. The following table shows the main parameters that should appear in a technical inquiry or purchase specification.
| Parameter | What the Buyer Should Confirm |
|---|---|
| High-voltage rating | Nominal voltage, maximum system voltage, and tap range |
| Low-voltage rating | Secondary voltage required by the plant or distribution network |
| Rated capacity | kVA or MVA based on calculated demand and future expansion |
| Frequency | Normally 50Hz or 60Hz, according to the local power system |
| Cooling | Natural or forced oil cooling, or air cooling for dry-type designs |
| Vector group | Required phase displacement and neutral configuration |
| Impedance | Short-circuit performance and voltage regulation requirements |
| Insulation level | Power-frequency withstand and lightning impulse withstand values |
Capacity should be calculated from the connected load, demand factor, power factor, and expected growth rather than simply adding the nameplate ratings of every load. For example, a plant with a calculated demand of 2.4MVA may evaluate a transformer around 3MVA, but the final margin depends on operating conditions, motor starting, harmonics, ambient temperature, and the owner’s loading policy. We recommend that the customer provide a load schedule so we can review the capacity selection before quotation.
Oil-immersed transformers use insulating liquid for winding insulation and heat transfer. They are commonly considered for outdoor substations, utility distribution, industrial plants, and projects where a relatively compact and efficient transformer is required. Typical configurations may include sealed-tank or conservator designs, off-circuit tap changers, radiators, temperature indicators, pressure relief devices, and other accessories selected for the project.
Oil-immersed construction requires proper attention to oil containment, fire separation, ventilation, inspection, and environmental conditions. The buyer should specify the insulation liquid type, required oil preservation arrangement, altitude, ambient temperature, and site installation requirements. We do not recommend selecting this type solely because its initial price appears lower; the installation environment and safety arrangement must also be suitable.
Dry-type transformers use solid insulation and air-based cooling instead of a liquid-filled tank. They may be suitable for indoor substations, commercial buildings, tunnels, high-occupancy facilities, or locations where liquid management is undesirable. Cast-resin and other dry-type designs should be evaluated for ventilation, enclosure protection, noise, partial discharge requirements, and the actual thermal environment.
Dry-type equipment can require more installation space or different ventilation provisions than an oil-immersed unit, depending on the design. Its suitability should therefore be judged by the complete project cost and risk profile rather than by transformer price alone. We can help compare both construction types when the application requirements are clearly defined.
35KV transformers are used in industrial distribution networks, mining operations, manufacturing plants, water-treatment facilities, utility substations, data-related infrastructure, and renewable-energy collection systems. They can connect incoming medium-voltage power to plant distribution equipment or raise the voltage from a generation or collection system for connection to a higher-voltage network. The appropriate design varies significantly between a stable utility substation and a site with large motors, fluctuating renewable output, or severe outdoor conditions.
Start with the nominal and maximum system voltage, secondary voltage, frequency, phase arrangement, grounding method, and expected fault level. Confirm whether the transformer will operate alone, in parallel with another transformer, or as part of a ring or radial distribution system. These details affect the winding arrangement, vector group, impedance, terminals, and protection design.
With competitive price and timely delivery, Liye sincerely hope to be your supplier and partner.
Prepare a load schedule that separates continuous loads, intermittent loads, motors, heaters, rectifiers, variable-frequency drives, and future loads. Include power factor and demand assumptions, because a transformer’s kVA or MVA rating is based on apparent power rather than only active power in kW. We also recommend reviewing ambient temperature and altitude, since environmental conditions can influence thermal performance and derating.
Tap arrangements may be off-circuit or on-load, depending on how frequently voltage adjustment is required and how the network is operated. Cooling and accessories should be selected from the actual rating and installation conditions, not copied from a different project. Possible requirements include winding temperature indication, oil temperature indication, pressure relief, Buchholz protection for applicable designs, surge arresters, marshalling boxes, monitoring devices, and cable or busbar terminals.
Ask the supplier which technical standard and edition will govern design, routine testing, documentation, and acceptance. IEC and IEEE-based specifications are both used in international projects, but the applicable requirements must be agreed in the purchase contract. Before production, review the outline drawing, nameplate data, terminal arrangement, dimensions, mass, lifting points, foundation loads, and shipping condition.
The price of a 35KV power transformer depends on capacity, winding material, insulation system, cooling method, accessories, enclosure, tap changer, testing requirements, packaging, and delivery terms. Copper windings may have a different cost profile from aluminum windings, while special insulation levels, low-loss requirements, or customized terminals can also affect the quotation. A low initial price is not meaningful if important accessories, testing, transport protection, or documentation are excluded.
Minimum order quantity is often project-dependent for medium-voltage transformers. A single customized unit may be possible, while repeat orders can improve design efficiency and spare-parts planning. Lead time should be confirmed after the technical specification is frozen, because approval drawings, material procurement, production, testing, and export packing can each affect the schedule.
When we evaluate a project inquiry, we look for a complete technical schedule instead of relying on a short product name. Buyers should compare each supplier on engineering response, design transparency, manufacturing capability, inspection process, packing method, documentation, and communication during approval. The supplier should clearly distinguish guaranteed values from typical values and identify any deviations from the customer’s specification.
One frequent mistake is ordering a transformer based only on “35kV” without confirming the maximum system voltage and insulation coordination. Another is selecting capacity from present demand while ignoring motor starting, power-factor correction, harmonic loads, or planned expansion. Buyers also sometimes compare quotations with different accessory lists, testing scopes, or delivery terms, which makes the apparent price difference unreliable.
To reduce these risks, we recommend using one standardized inquiry sheet for every supplier. Include the single-line diagram, load schedule, site conditions, required standards, delivery location, preferred transformer type, and inspection expectations. A technically comparable quotation is usually more valuable than a rapidly submitted but incomplete offer.
At Liye, we support B2B customers with 35KV power transformer selection, technical clarification, configuration review, production coordination, and export-oriented documentation. We can discuss oil-immersed and dry-type alternatives according to the project’s electrical and installation requirements. Our role is to help convert the customer’s system information into a practical transformer specification rather than recommend a generic model without application context.
For an accurate proposal, send us the required primary and secondary voltage, capacity, frequency, vector group, tap requirement, installation environment, applicable standard, quantity, destination, and requested delivery date. If some information is not yet available, we can identify the missing decision points and state the assumptions used for preliminary selection. This approach helps engineering teams, contractors, distributors, and project purchasers move from initial inquiry to a technically reviewable quotation.
The right 35KV power transformer is the one that matches the complete electrical system, not merely the nominal voltage. Confirm the voltage class, capacity, insulation level, vector group, impedance, cooling method, installation environment, protection requirements, and applicable standards before placing an order. Then compare suppliers using the same technical schedule, testing scope, documentation list, and delivery terms.
As your next step, prepare the single-line diagram and load data, identify whether oil-immersed or dry-type construction is appropriate, and request a detailed technical quotation. Contact Liye with your project parameters, and we can review the configuration, clarify specifications, and provide a practical 35KV transformer solution for your application.
Contact us to discuss your requirements of 35KV power transformer. Our experienced sales team can help you identify the options that best suit your needs.