Load Assessment Before Selecting a Box-Type Substation

Collect charging power profile and simultaneous factor

Start from the charging station master plan: number of DC fast chargers, AC chargers, rated output per charger, expected peak occupancy, and future expansion bays. EV charging load is not continuous like a conventional distribution load; simultaneous high-power DC sessions create step loading, higher RMS current, and frequent load swings. The box-type substation transformer should be sized from the calculated diversified peak demand, not from the arithmetic sum of all charger nameplates.

For Xinda/Xinda export packages, the substation scope can be built around YB-12 European-style prefabricated compact units, YBP box-type units, or metal-clad prefabricated substations, with oil-immersed or dry-type transformers selected according to site fire, ventilation, and maintenance policy . The final kVA rating must come from the charging-load study.

Define inlet voltage, outlet voltage, and network scheme

Most urban and highway charging hubs use medium-voltage inlet and 0.4 kV low-voltage outlet for AC/DC charger distribution. Xinda’s YB-12 product is documented for 12 kV, 50 Hz three-phase systems with capacity configurations up to 1600 kVA, suitable for ring-main and radial terminal supply . YBP is documented with model YBP-12/0.4, HV 12 kV, LV 0.4 kV, and customizable capacity from 10 kVA to 5000 kVA . For projects requiring 35 kV, 110 kV, or higher inlet, treat the package as a custom prefabricated substation or conventional substation and confirm switchgear, transformer, and protection scope separately rather than using a standard 12 kV box.

Transformer Selection for Energy-Efficient EV Substations

Oil-immersed vs dry-type in charging applications

Xinda’s box-type substation options allow oil-immersed, fully sealed, or dry-type transformers. YB-12 material states the transformer compartment can use oil-immersed, fully sealed, or dry-type units, while YBP is described with low-loss transformer, energy-saving and low-noise operation . For fully outdoor open sites with large transformers, oil-immersed units are usually evaluated for cost and capacity; for semi-indoor, underground, or fire-sensitive commercial charging buildings, dry-type units are evaluated for reduced flammable-fluid risk. The final choice should be based on local fire code, enclosure ventilation, transformer rating, and lifecycle maintenance, not on a fixed rule.

Xinda’s wider transformer portfolio includes 10 kV S11-M, S13-M.RL fully sealed/wound-core oil units, 35 kV S11/SZ11 oil units, 110 kV and 220 kV power transformers, 10 kV SC(B)10 cast-resin and SG(B)10 non-encapsulated dry-type units, and SBH15-M/SCBH15-M amorphous products . For a charging-only box substation, the model must be confirmed by capacity and standard; amorphous may be considered where no-load loss reduction justifies first cost.

Specify energy-efficiency level instead of “energy-saving” only

Do not accept “energy-efficient” as a specification. Request guaranteed no-load loss, load loss, impedance, tap range, temperature rise class, and test standard. For export projects, state IEC 60076 or the destination-grid efficiency class; for China-domestic tenders, reference GB 20052 or the applicable provincial utility specification. Xinda’s corporate materials describe energy-saving smart transformers and a full transformer manufacturing scope, but loss guarantees must be model-specific and written into the purchase order .

On-load or off-circuit tap changing for charger voltage stability

DC chargers and site transformers can interact with source-voltage variation, cable drop, and local load growth. If the medium-voltage inlet is expected to vary or the charging hub will expand in phases, evaluate on-load tap changing. Xinda’s 35 kV SZ11 platform is documented with on-load voltage regulation using manual, electric, or automatic operation ; for 12 kV box substations, confirm whether OLTC, off-circuit taps, or automatic AVR at the charger/system level is more appropriate. OLTC is not automatic for every charging station—specify range and step size from the utility voltage profile.

High-Voltage, Low-Voltage, and Protection Configuration

HV switchgear: load switch, ring main, or circuit breaker

YB-12 documentation states the high-voltage side typically uses load-break switches and optionally vacuum circuit breakers, with anti-misoperation interlocking and optional SF6 ring-main units such as XGN20-12L, HXGN15A, or HXGN17 . YBP documentation supports terminal, ring-network, and dual-power switching schemes . For EV hubs with large inrush, fault-feeder coordination, or utility protection requirements, vacuum circuit breakers and protective relays should be evaluated instead of load-switch-fuse only.

Xinda’s wider HV lineup includes KYN61-40.5, KYN28A-12, HXGN-12, and XGN2-12 . For a 12 kV charging box, request the single-line diagram, short-circuit rating, relay types, metering class, and remote-control protocol before production.

LV distribution for multiple charger feeders

The low-voltage compartment should be specified by number of outgoing feeders, charger group segregation, branch protection, and smart metering. YB-12 uses GGD-type distribution boards as a documented option ; Xinda’s general LV range also includes GCK, GCS, and MNS withdrawable switchgear plus GGD fixed switchgear . For charging stations, separate AC charger feeders, DC power-module feeders, HVAC, lighting, and monitoring circuits; avoid overloading one LV panel with mixed EV and auxiliary loads.

Protection, metering, and power quality devices

A charging box substation should include HV overcurrent/earth-fault protection, transformer protection according to rating, LV circuit breakers with selective coordination, and optional high/low-voltage metering. YB-12 and YBP both mention complete protection and optional metering ; YBP adds five-prevention interlock . For EV loads, also specify:

• harmonic measurement and mitigation strategy based on charger THDi;
• reactive compensation or SVG/STATCOM study for low power factor during light-load or converter-dominated operation;
• surge protection for LV charger circuits and communication systems;
• SCADA/modbus/IEC 60870/61850 mapping for remote reset, load monitoring, and alarm reporting.

Published EV industry guidance uses IEC 62271-202 for prefabricated substations, IEC 60076 for transformers, IEC 61439 for LV assemblies, and IEC 61000 for harmonic/emission coordination; China charging-station design may additionally reference GB/T 50966 and related charging standards . Confirm the exact edition and local amendments in the tender.

Enclosure, Cooling, and Site-Environment Configuration

Box style: YB-12, YBP, metal-clad, or American-style

For European-style three-compartment EV hubs, YB-12 is documented for urban, commercial, industrial, and temporary sites with compact footprint and factory assembly . YBP is documented with I-shape or triangle-shape compartments, separate HV/transformer/LV rooms, IP4X HV, IP5X transformer, IP4X LV in its parameter table, and application in residential, industrial, municipal, parking, subway, airport, port, and coastal salt-fog conditions . Metal-clad prefabricated substation is listed in Xinda’s product menu for customized enclosure and complete MV/LV/transformer integration . Choose by land availability, maintenance access, cable routing, and local appearance requirements—not by the generic term “box.”

Thermal management for high-density charging load

Charging substations accumulate heat from transformer losses, LV busbars, and charger-adjacent compartments. YB-12 documentation describes double-layer roof insulation, separate HV/LV ceilings, transformer-room anti-condensation, automatic temperature monitoring, heating/cooling devices, natural ventilation, and optional forced ventilation with dust filters . YBP documentation lists natural cooling and optional forced-air cooling . For fast-charging hubs, request a thermal calculation that includes diversified charger load, transformer loss guarantee, solar gain on enclosure, ambient design temperature, and forced-cooling staging.

Corrosion, ingress protection, and harsh-site options

YB-12 enclosure options include aluminum alloy, steel plate, composite plate, stainless steel, and non-metallic glass-fiber-reinforced concrete . YBP offers high-quality steel or aluminum alloy with anti-corrosion, rainproof, sun-proof, dustproof, and UV-resistant treatment . For coastal charging stations, port hubs, or industrial pollution zones, specify corrosion class, IP rating, gasket material, heater/dehumidifier setpoints, and cable-entry sealing. Standard YB-12 environment limits are +40°C maximum, −25°C minimum, altitude ≤2000 m standard up to 4000 m with special components, relative humidity ≤90% at +25°C, and outdoor wind ≤35 m/s ; deviations must be written as custom design conditions.

Smart Monitoring and Lifecycle O&M for EV Box Substations

IoT monitoring parameters to include

Xinda’s technical-article materials cover IoT transformer online monitoring and predictive maintenance, including temperature, load, condition data, and centralized operation/maintenance . For EV charging boxes, specify winding/oil or dry-type sensor temperature, LV feeder currents, power factor, harmonic profile, tap position if OLTC, door status, smoke/fire interface, and communication alarms. This supports peak-load management, early overload warning, and reduced site visits for unattended charging parks.

Preventive maintenance and documentation

Factory prefabrication reduces site wiring but does not remove maintenance. For YB-12/YBP packages, keep supplier documentation for HV operation, fuse replacement, transformer oil or dry-type inspection, LV breaker testing, ventilation/filter cleaning, and five-prevention verification. YBP material states components are assembled, insulated, and tested in the factory, with on-site work limited to foundation fixing and cable connection ; YB-12 states reduced on-site installation and short commissioning cycles . The O&M manual should still define inspection intervals by load hours, not by calendar only.

Xinda Sourcing Information for EV Charging Projects

Xinda Transformer Co., Ltd. is located at 38 Jingsan Road, Fenghuang Industrial Park, Dongchangfu District, Liaocheng, Shandong . Public company data state registered capital RMB 150 million, 150 mu site, 53,000 m² building area, 260+ employees including 4 senior engineers and 12 engineers, 1 invention patent and 14 utility-model patents, 470+ production equipment units, annual output 5 million kVA, and installed capacity for 220 kV-and-below transformers up to 10 million kVA per year together with supporting switchgear . For an EV grid-expansion inquiry, send the following so the manufacturer can return a non-generic box-substation proposal:

Inquiry data sheet for charger substation

• Site address, utility inlet voltage, frequency, grounding system, and available short-circuit current
• Total DC/AC charger rating, number of guns, expected simultaneous factor, daily load curve
• Required substation kVA, HV/LV voltages, vector group, tap range, OLTC or off-circuit
• Transformer type preference: oil-immersed sealed, dry-type cast/non-encapsulated, amorphous, or project-defined
• HV scheme: load switch ring main, vacuum breaker, dual inlet, protection relay list
• LV scheme: GGD/GCK/GCS/MNS, feeder count, charger grouping, metering, compensation, harmonic filter
• Enclosure: YB-12/YBP/metal-clad/American-style, material, IP, color, anti-corrosion class
• Environment: ambient temperature range, altitude, humidity, salt fog, dust, wind, seismic
• Monitoring: IoT sensors, SCADA protocol, alarm points, remote reset
• Standards: GB/T 17467, SD320, IEC 62271-202, IEC 60076, IEC 61439, local charging-station code, and utility type-test requirements

This configuration method keeps the EV box-type substation energy-efficient, compliant, and scalable without using assumed loss values, fixed kVA-per-charger ratios, or unverified product claims.