Basic Electrical Rating and Vector Group Options

Voltage ratio and system frequency

For a 110kV/63000kVA unit, the enquiry must state the high-voltage rated voltage, highest system voltage, low-voltage rated voltage, frequency, and whether 50Hz or 60Hz is required. Xinda/Xinda product materials list 110KV power transformers and oil-immersed platforms from 10kV/35kV/110kV/220kV, so the 110kV class can be quoted as a step-down power transformer; the exact HV/LV combination should be defined by the substation single-line diagram rather than assumed .

The low-voltage side may be 10kV, 35kV, or another distribution voltage depending on the downstream switchgear and load centers. If the project also needs 35kV and 10kV buses, evaluate a three-winding transformer instead of two separate two-winding units; the final choice depends on load split, reserve capacity, and protection coordination.

Vector group and neutral earthing

Vector group must match system earthing, parallel-running transformers, and protection settings. Common 110kV step-down options include YNd, YNyn, or YNyn with additional windings for auxiliary/distribution purposes; the ordered group should be confirmed by the utility or EPC design. Xinda’s general transformer portfolio includes oil-immersed power units, and project reference such as S11-63000/110 for Shenxian Shuangyuan shows 110kV-class delivery experience, but vector group and neutral insulation must still be specified per station, not copied from a reference unit .

For neutral earthing, state whether the 110kV neutral is solidly earthed, resistance earthed, reactance earthed, or effectively earthed per local grid code. The low-voltage neutral treatment should be specified separately because it affects relay settings, grounding transformer requirements, and LV switchgear insulation.

Core, Winding, and Loss Configuration

Winding conductor and insulation system

For a 63MVA 110kV power transformer, request copper or aluminum winding specification in writing. Xinda’s oil-immersed product descriptions reference oxygen-free copper windings and cold-rolled silicon-steel cores for energy-saving designs; the purchase order should fix conductor material, insulation class, creepage/clearance for the specified altitude and pollution level, and moisture-control method for the tank .

Do not accept “standard insulation” as a specification. The enquiry should state mineral oil or alternative fluid, pressboard/DMD/composite insulation system, bubble/dissipation factor acceptance, and impulse insulation levels according to IEC 60076-3 or the local grid standard. For 110kV, Um exceeds 72.5kV; lightning impulse testing and the applicable AC/induced/switching-impulse program should be defined in the type/routine test schedule .

No-load loss, load loss, and efficiency guarantee

Specify guaranteed no-load loss, load loss, impedance, and tolerance instead of only asking for “energy-saving.” IEC 60076-1 routine testing covers winding resistance, ratio, no-load loss/current, impedance and load loss; type testing covers temperature rise, impulse, and—where contracted—short-circuit withstand . Xinda’s corporate materials describe energy-saving smart transformers and full transformer manufacturing, but loss values are model-specific and must be returned by the manufacturer against your rated tap, cooling stage, and ambient conditions .

If the project is loss-capitalized, ask for capitalized-lifecycle evaluation: bid comparison using guaranteed P0/Pk, discount rate, load factor, and emergency loading. This is more useful than comparing nameplate prices for 110kV/63MVA units.

Tap-Changer Configuration: OLTC vs Off-Circuit

When on-load tap changing is required

For 110kV main transformers supplying variable grid voltage, long feeders, industrial motor loads, or renewable interconnection, specify OLTC. Xinda’s 35kV SZ11 product information states SZ11 supports on-load voltage regulation with manual, electric, or automatic operation; for 110kV/63MVA the same regulation philosophy applies but the tap range, step size, drive, and control system must be calculated from source-voltage variation, line drop, transformer regulation, and load profile .

OLTC selection should follow IEC 60214-1 for performance/tests and IEC/IEEE 60214-2 for application guidance. Define rated step voltage, maximum tap current, transition type—resistor, reactor, or vacuum—number of positions, continuous/consecutive operation duty, and maintenance interval by operation count rather than calendar only .

Off-circuit taps for stable networks

If the 110kV supply and LV load are stable, and ratio adjustment can be made during planned outages, an off-circuit/de-energized tap changer may be sufficient. It reduces cost, oil-compartment complexity, and maintenance. The enquiry should still state the required number of taps, principal tap, and whether future load growth may require conversion to OLTC—because retrofitting OLTC into a fixed-tap power transformer often requires regulating winding, tank space, and insulation changes not originally designed .

Automatic voltage regulation and SCADA interface

For automatic operation, specify AVR or VQC control, measured voltage point, bandwidth, time delay, line-drop compensation, parallel-transformer load-balancing mode, and remote signals. Xinda’s IoT/monitoring technical articles describe online transformer monitoring, predictive maintenance, and centralized O&M data; for a 110kV order, include tap-position feedback, motor-drive status, alarm/trip signals, and Modbus/IEC 60870/61850 mapping in the control specification .

Cooling, Thermal Management, and Ancillary Protection

Cooling method and staged ratings

Oil-immersed 110kV/63MVA units may use ONAN, ONAN/ONAF, or stronger forced cooling depending on ambient temperature, altitude, noise limits, and site footprint. The purchase specification should state base rating under natural cooling and upgraded rating under forced stages, with fan/pump control setpoints, redundancy, and loss of forced-cooling rules.

Xinda’s factory resources include silicon-steel slitting/cutting, core winding, automatic coil winding, foil winding, and busbar processing; for 110kV production these support core/winding build but do not determine cooling class by themselves . Thermal acceptance should be based on IEC 60076-2 temperature-rise type test for the ordered cooling configuration, not on catalogue cooling labels.

Tank, conservator, and oil preservation

Specify preservationsystem: free-breathing with conservator and breather, sealed tank, nitrogen blanket, or dry-air transport/commissioning arrangement. For 110kV power transformers, state oil-processing requirements, vacuum filling, moisture limits, BDV/dissolved-water/acidity acceptance per the selected fluid standard, and gas-relay/pressure-relief/buchholz functions where used.

Xinda’s oil-immersed product descriptions reference radiators, optional conservator/capsule corrugated tank, gas relay with gas-collecting device, and winding/oil temperature monitoring for S11/SZ11-class units; for 110kV/63MVA the same accessory logic applies but the sizes, relay types, and monitoring channels must be confirmed by thermal and protection design .

Protection sensors and monitoring package

For a complete 110kV offer, include OTI/WTI or PT100/RTD winding sensors, oil-temperature gauge, pressure relief, sudden-pressure relay where specified, moisture-in-oil, DGA options for critical substations, partial-discharge sensors for new HV/MV-critical units, and smart monitoring gateway. Xinda’s hdxdbyq technical section publishes IoT online monitoring and core-inspection articles; use them as reference for the monitoring scope, but require project-specific calibration ranges, alarm setpoints, and SCADA point list .

Short-Circuit Strength, Standards, and Factory Test Plan

Short-circuit duty and mechanical robustness

Provide system short-circuit capacity at 110kV and LV terminals, X/R or symmetrical RMS fault current, fault duration, and parallel/series winding arrangement. IEC 60076-5 covers short-circuit withstand; sudden-short-circuit type testing may be requested for critical utility/industrial projects, while routine production uses design verification, impedance/ratio/resistance tests, and factory mechanical inspection .

Xinda references 110kV project experience through S11-63000/110 and states overall capability for 220kV-and-below transformers with 470+ production equipment units and 5.3万㎡ building area; for a 63MVA 110kV order, request winding bracing method, core clamping, lead support, and either a valid type-test certificate for an identical design or a new short-circuit type test if the tender requires it .

Standards and documentation matrix

State the primary standard—IEC 60076 series for most export projects, GB/T 1094 series for China utility projects, or IEEE C57 where North American/joint-venture specs apply. Add IEC 60296 for mineral oil, IEC 62770/IEEE C57.147 for natural ester if specified, IEC 60137 for bushings, IEC 60214 for tap changer, and local grid amendments for impulse levels, sound level, seismic, and environmental compliance .

The factory test plan should separate routine, type, and special tests:

• Routine: winding resistance at all taps, ratio/vector group, insulation resistance, no-load loss/current, impedance/load loss, applied/induced AC withstand, oil tests, accessory functional checks
• Type: temperature rise, lightning impulse, and—where required—short-circuit withstand, sound level, PD baseline
• Special: FRA, PD measurement, zero-sequence impedance, harmonic no-load study for converter loads, seismic/transport simulation, DGA before/after type tests

Xinda’s factory test resources and 110kV/220kV product scope support FAT witnessing; the bid should name witness points, independent laboratory use, and English test reports for export handover .

Switchgear, Substation Integration, and Complete-Package Options

High-voltage and low-voltage switchgear interface

A 110kV/63MVA transformer is rarely purchased alone. Specify HV incoming switchgear—AIS, GIS, or metal-clad—LV distribution, protection relays, metering, and cable terminations. Xinda’s HV list includes KYN61-40.5, KYN28A-12, HXGN-12, XGN2-12; LV list includes GCK, GCS, MNS, GGD . For 110kV incoming, confirm whether the project requires 110kV GIS/AIS panels supplied separately or through the transformer manufacturer’s switchgear partners; do not assume a 12kV/40.5kV cabinet covers 110kV switching.

Prefabricated substation or conventional civil substation

If the 63MVA unit serves a compact industrial park, EV hub, mining site, or temporary high-load camp, evaluate YB-12 European-style, metal-clad prefabricated, or custom prefabricated substation packages. Xinda’s hdxdbyq product list includes YB-12 European-style compact substation and metal-clad prefabricated substation; however, a 110kV/63MVA main transformer usually requires a designed switchyard rather than a standard 12kV box, so the package scope must be confirmed by layout, fire separation, oil containment, and utility approval .

For conventional substations, request civil coordination drawings, cable trench, oil pit/secondary containment, fire detection, ventilation/heating, crane/lifting clearance, and road/roller access. Xinda’s Chinese-site materials state 150mu site, 260+ staff, 4 senior engineers/12 engineers, 1 invention/14 utility-model patents, and 220kV-and-below 1000万kVA annual installed capability with switchgear; use these for supplier-capacity evaluation, not for substituting detailed substation engineering .

Special applications: rectifier, renewable, and industrial loads

If the 63MVA transformer feeds rectifiers, furnaces, PV/wind collector, BESS, or harmonic-rich drives, specify converter configuration, harmonic spectrum, K-factor/harmonic derating, screening/shielding, and separate converter winding tests. Xinda’s special-transformer list includes rectifier transformers and the hdxdbyq case list includes power-generation/machinery/rural applications; for 110kV special duty, request a dedicated thermal/harmonic study and type-test scope rather than a standard grid transformer quotation .

Supplier Qualification and Procurement Data Sheet

Xinda capability check for 110kV/63MVA bid

Request written confirmation of 110kV/63MVA reference units, factory routine/type/special test facilities, OLTC brand and compartment design, core/winding material certificates, impulsetest capability, transport weight/dimension envelope, sea-worthy packing, installation supervision, and spare-part list. Xinda’s public references include S11-63000/110 at Shenxian Shuangyuan, S11-10000/35 at Shandong Xinfa, and S11-6300/35 at Heilongjiang Jiansanjiang; for a new 110kV/63MVA OLTC order, ask for model-specific type-test reports instead of relying on awards or general qualifications .

Also verify utility prequalification relevant to the destination market. Xinda’s Chinese-site news states State Grid 2026 substation-equipment prequalification and Southern Grid new-type converter-equipment award; these support domestic grid credibility but should not replace IEC/local-utility type-test and factory-audit requirements for export projects .

Minimum enquiry information to receive an accurate configuration

Send to the manufacturer:

• Rated 63MVA at 110kV with actual HV/LV voltages, frequency, vector group, and neutral earthing
• System short-circuit current at both terminals, X/R, fault duration, and parallel-operation requirements
• Load profile, future growth, harmonic/converter duty, and renewable/intermittent generation if any
• Tap range and control mode: off-circuit, OLTC manual/electric/automatic, step size, transition technology
• Cooling class, ambient temperature, altitude, humidity, salt fog, dust, noise limit, and fire-code requirements
• Insulation fluid: mineral oil, natural/synthetic ester, or project-specified alternative
• Protection and monitoring: relays, buchholz/pressure, OTI/WTI, DGA/PD, SCADA protocol
• Standards: IEC 60076/60214/60137/60296 or GB/IEEE/local grid; routine/type/special test witness plan
• Switchgear/substation scope: 110kV AIS/GIS, LV switchgear, prefabricated civil package, cabling, commissioning

This configuration framework lets the buyer compare 110kV/63000kVA offers on technical scope and lifecycle risk instead of price alone, while staying within verified Xinda product, case, and factory data.