Engineered, inspected, and tested for the duty
Engineering
Engineering review covers short-circuit withstand, thermal duty and insulation coordination against the applicable IEEE C57 or project requirements. Design calculations, including finite-element analysis where required, support the proposed design. Drawings, nameplate and test plan are issued for the specified buyer and utility approvals before the relevant production stages.
Inspection
A stage-gated inspection and test plan with hold, witness and review points is issued for your sign-off before production. For liquid-filled power units, stages include core build, winding, assembly, drying and oil processing. Core steel, conductor and insulation traceability is included in the plan. Your inspector is welcome at the agreed hold and witness points.
Testing
Factory tests verify the ordered transformer against its specification and applicable standard. The test plan defines the required electrical, dielectric and functional checks, supporting design tests, and any additional measurements. Buyer witness points are scheduled with your engineer at order.
Documentation
Test reports, final drawings and the operating and maintenance manual form the digital dossier, kept by serial number. Oil certificates, frequency-response and dissolved-gas baselines, impact-recorder logs and commissioning reports are included where applicable to the equipment and supplied scope.
Test program, inspection points, standards, and interfaces
Factory test program — project scope and IEEE C57.12.90
The detailed program below covers tests and records considered for power-transformer orders. Distribution transformers use the tests applicable to their design and specified standard. The agreed plan identifies required measurements, design evidence and additional tests for each package.
| Test | Scope |
|---|---|
| Factory measurements and checks — scope set for the equipment | |
| Winding resistance | Specified windings and tap positions |
| Ratio, polarity, and phase relation | Specified tap positions and connections |
| No-load loss and excitation current | At rated voltage; 110 % excitation where required |
| Load loss and impedance | At rated current and specified taps and cooling-stage ratings |
| Zero-sequence impedance | Where specified for grounded-wye systems and relay settings |
| Applied-voltage test | Low-frequency dielectric; test levels for the specified insulation class |
| Induced-voltage test with partial discharge | Partial-discharge measurement, enhancement and one-hour levels where required by the selected test procedure |
| Lightning impulse | Full and chopped wave where required, at the specified terminals and test levels |
| Insulation power factor and resistance | Windings and bushings; C1 / C2 measurements where applicable |
| Core ground insulation | Core-to-ground and core-to-frame |
| Leak and pressure test | Liquid-filled tanks and radiators, as applicable |
| Sweep-frequency response baseline | When specified: reference fingerprint before shipment, compared at site |
| Oil tests | For liquid-filled equipment: specified dielectric strength, moisture, power factor, corrosive sulfur, furans and DGA tests; pre- and post-dielectric samples where required |
| Current transformers | Where fitted: ratio, polarity and excitation |
| Functional checks | Cooling, controls, alarms, and LTC operation where fitted |
| Design tests — applicable reports or project testing | |
| Temperature rise | Specified cooling stages; repeated on individual units when required |
| Audible sound | Applicable sound standard and project limits; NEMA TR-1 where specified; unit repeat tests when required |
| Lifting, jacking, and transport fixtures | Mechanical verification |
| Other — when specified | |
| Short-circuit withstand verification | Test or calculation and similar-design evidence to the agreed specification; IEEE C57.12.90 and finite-element force analysis where applicable |
| Radio-influence voltage | Corona check on bushings and terminals |
| Extended temperature-rise or sound program | Per your specification |
Inspection and test plan
The stages below illustrate a liquid-filled power-transformer inspection plan. Equipment-specific plans identify the applicable stages and mark each point hold, witness or review.
- Material receipt: core steel, conductor and insulation traceability
- Core stacking complete
- Winding completion, each winding
- Core-and-coil assembly, before drying
- Vacuum drying end point: moisture and dew point
- Tanking and oil filling under vacuum
- Final assembly and pre-test checks
- Factory acceptance test — agreed buyer witness points
- Packing, specified transport monitoring and release for shipment
Site program
Site services and measurements are selected for the equipment, transport condition and agreed commissioning scope.
- Receiving inspection and any impact-recorder review
- For gas-shipped units: dew-point and oxygen check before oil filling
- SFRA compared with the factory baseline where specified
- Pre-energization tests for the equipment; IEEE C57.152 where applicable
- DGA at energization and after the first month of service when included in the site program
Standards
The applicable standards, editions and technical exceptions are identified in the quotation. The references below are selected according to product, voltage class, duty and supplied accessories.
IEEE C57.12.00 · C57.12.10 · C57.12.90 · C57.91 · C57.110 · C57.159 · C57.104 · C57.149 · C57.152 · C57.106 · C57.147 · C57.19.00 · C57.13 · C57.131 · C57.93 · IEEE 693 · NEMA TR-1 · ASTM D3487
Built to IEC 60076 or regional specifications when the project requires it.
Interfaces and submittals
Power-transformer interface examples: multi-ratio bushing current transformers, relay accuracy class C800 where specified, neutral CT on grounded-wye windings · control power 125 V DC and 120/240 V AC, 480 V for cooling where required · alarm and trip contacts for temperature, pressure, liquid level and gas · DNP3 or IEC 61850 monitoring options · approval package: outline, nameplate, control schematics, CT curves and bushing drawings as applicable. Distribution-package interfaces are set by the installation and equipment specification.
Bring your inspector
Your engineer or third-party inspector is welcome at the agreed hold points and factory acceptance test. We schedule it with you at order.
Request a quotation