TRANSFORMER APPLICATION

Transformers for BESS

Prepare a transformer enquiry around your battery energy storage system's actual AC interface and operating duty. Whether you are building a PCS block, adding storage to an existing plant or connecting storage at a factory, define the equipment scope, charge and discharge requirements, and site conditions before comparing quotations.

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Start with your project task

Specify a transformer for a new PCS block

Your power conversion system needs a transformer interface to the project AC network. Start with the selected PCS arrangement and the boundary between the equipment packages.

Send these inputs: PCS manufacturer, model and document revision; number of converters; single-line diagram; converter-side AC data; project-side voltage and frequency; proposed transformer rating, quantity and destination.
Review and coordination: Identify the converter grouping, electrical connections and terminals covered by the requirement. Separate the transformer from switchgear, PCS, enclosure or skid items that may be supplied under another package.
Expected output: A transformer RFQ with a defined interface schedule, equipment inclusions and unresolved questions for the PCS supplier and project designer.

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Add storage or change an existing storage installation

An existing solar or storage transformer should not be assumed suitable for a new PCS, additional operating hours or a revised dispatch strategy.

Send these inputs: Existing transformer nameplate and drawings, original duty requirements, proposed PCS information, revised single-line diagram, available operating records, site measurements and planned outage window.
Review and coordination: Compare the retained equipment and interfaces with the proposed duty. Identify whether the request concerns a new transformer, a replacement or a review of existing equipment; do not treat equal nameplate capacity as proof of interchangeability.
Expected output: A clear list of retained interfaces, changed requirements and decisions needed before a replacement or expansion quotation.

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Connect storage to a factory or commercial facility

Behind-the-meter storage needs to fit the site's electrical distribution and operating plan, whether the aim is load management or a separately engineered standby arrangement.

Send these inputs: Facility single-line diagram, connection point, import and export limits, proposed operating modes, PCS data, available transformer-room or outdoor layout, and any essential-load or standby requirements.
Review and coordination: Establish the transformer supply requirement within the facility design. Keep the site's switching, protection, auxiliary supply and control responsibilities visible, especially when storage is expected to operate during a grid outage.
Expected output: A component supply brief that the facility designer can compare with the existing distribution system, with system-level decisions separated from the transformer offer.

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Conditions that affect configuration

Charge, discharge and energized operating periods

The required operating envelope is more useful than a generic daily cycle count. Include charging, discharging, idle-but-energized periods and any specified reactive-power service when establishing the thermal and loss evaluation basis.

Information to provide: Charge and discharge power schedules, durations and limits; required reactive duty; ambient conditions; expected energized hours; proposed overload requirements with duration; and the loss evaluation conditions used to compare offers.

PCS electrical and winding interface

A bidirectional label does not establish a compatible connection. Winding arrangement, insulation and converter grouping need to match the selected PCS requirements, including relevant power-electronics effects.

Information to provide: Current PCS transformer-interface documentation, AC voltage and current data, permitted winding arrangements, harmonic information and any specified shielding or insulation requirements. Keep battery DC voltage separate from the transformer AC ratings.

Earthing, protection and network connection

The transformer is one part of the complete electrical system. Its proposed connection and characteristics need review against the project's earthing, fault and protection requirements, not an assumed standard arrangement.

Information to provide: Network voltage and frequency, applicable project specification and revision, earthing philosophy, required vector group and impedance if defined, fault-level information, terminal arrangements and the party responsible for protection coordination.

Installation space, cooling and site requirements

A compact footprint alone does not establish a workable installation. Heat rejection, maintenance access, cable interfaces and the site's safety strategy need to be considered together with transformer technology.

Information to provide: Indoor, outdoor or skid layout; temperature, altitude and exposure conditions; ventilation or enclosure cooling concept; access and foundation limits; cable entry; noise criteria; and applicable separation, containment and fire-safety requirements from the project team.

Explore suitable product options

Oil-immersed transformers

Explore this category where the installation design permits liquid-filled equipment. The proposed BESS duty, PCS interface, site layout, cooling and containment requirements still need configuration-specific review.

Review product range

Dry-type transformers

Explore this category where the project calls for an oil-free transformer. Confirm electrical suitability, enclosure conditions and heat rejection; an indoor or containerized location alone does not establish PCS compatibility.

Review product range

Documents by project stage

RFQ and comparable supply scope

State the project task, quantities, requested schedule and known technical inputs. Compare the same equipment boundary, loss conditions, accessories, tests and exclusions. Keep missing information on a question list instead of allowing different assumptions to appear as equivalent offers.

Stage: quotation

Configuration and interface agreement

Agree the offered electrical data, outline and terminal drawings, dimensions and weight for the selected configuration. Define temperature, alarm, trip and cooling signals, terminal details and any communication interface included in supply. Resolve deviations with the responsible PCS and project teams before ordering.

Stage: design approval

Inspection, delivery and site handover

Agree the inspection plan, acceptance criteria and required records, including any special or witnessed tests. Confirm the manuals, accessory information and shipment documents expected at delivery. Assign installation, protection settings, commissioning and final system acceptance to the relevant project parties.

Stage: delivery

Scope and coordination

This enquiry concerns transformer equipment and documents expressly included in the quotation. Battery systems, PCS controls, EMS, switchgear, site safety design and grid-connection approval are separate responsibilities unless specifically agreed. Transformer supply alone does not establish whole-system efficiency, revenue, black-start capability or uninterrupted backup operation.

Questions before requesting a quotation

Can the battery's MWh capacity determine the transformer rating?

No. MWh describes stored energy, not the complete AC power requirement. Send the PCS data and operating schedule alongside the battery capacity, and have the project designer establish the required transformer duty and rating basis.

Does a BESS always need a special bidirectional transformer?

Power-flow direction is only part of the requirement. Do not accept or reject equipment from that label alone: compare the proposed transformer against the actual converter interface, operating envelope and project requirements.

Will the transformer make the BESS grid-forming or black-start capable?

Those are system-level functions involving the PCS, controls and the electrical installation. If required, identify them in the project brief so the responsible teams can define the transformer interface; they are not implied by a transformer purchase.

Can I begin an enquiry before the PCS selection is final?

Yes. Send the project role, known connection details, site layout, quantity and schedule, and state which PCS or operating decisions are still open. The discussion can clarify the missing inputs without presenting an unconfirmed configuration as a final offer.

Send your project requirements

Share the voltage, capacity, installation conditions and project specification. A document link is optional.

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