Views: 0 Author: Site Editor Publish Time: 2026-09-30 Origin: Site
A transformer can pass its electrical tests and still arrive with a rating plate that sends the wrong information to the site team. A missing cooling-stage rating, a reversed tap table or a serial number copied from the previous unit can create questions just when the equipment is ready for installation.
Transformer nameplate data review should therefore end with a practical answer: does this plate describe this transformer, in its approved final configuration? For EPC buyers and factory inspectors, the useful check is a line-by-line comparison of the installed plate, the approved nameplate drawing and the relevant factory acceptance test (FAT) records.
Use a clear photograph of the permanent plate on the actual unit. A drawing marked “approved” proves that a layout was accepted; it does not prove that the correct plate was manufactured or attached. Record the transformer serial number, project equipment tag and nameplate drawing revision before reviewing the electrical values.
Keep the approved data sheet, connection diagram, tap schedule and serial-specific FAT report beside the photograph. Where the contract calls for IEC 60076-1, check the adopted edition and the purchaser's additional marking requirements. The checklist below is a practical review aid, not a replacement for the specified standard or utility format.
Read the kVA or MVA value together with its cooling designation. If the approved design has separate natural-cooling and forced-cooling ratings, the plate must make their relationship clear. The largest printed capacity should not be interpreted as the capacity available with fans or pumps out of service.
For example, an illustrative 20/25 MVA ONAN/ONAF rating describes two assigned duties. Printing only “25 MVA” removes information needed to interpret the lower cooling stage. Before accepting a replacement plate, confirm that the cooling equipment and approved thermal evidence support both assigned ratings. The temperature-rise FAT guide explains the related test review.
Check rated current against the relevant winding voltage and power rating. For a balanced three-phase winding, the basic cross-check is I = S / (√3 × U), using VA and line-to-line volts. Thus, 1,000 kVA at 11 kV gives approximately 52.5 A; at 0.4 kV it gives approximately 1,443 A. These are illustrative calculations, not ratings for a particular Zisheng transformer. Multi-winding loading combinations and tapping duties require their own approved data.
Check each winding separately. Confirm the voltage unit, phase count, frequency and connection symbol against the approved diagram. Do not confuse a winding's rated operating voltage with its insulation level or highest voltage for equipment. A plate containing both types of information must label them clearly.
A connection-symbol discrepancy needs engineering review. If the plate says one vector group and the approved drawing says another, inspect the test record and actual connections before deciding which record is wrong. Replacing the plate alone is appropriate only after the installed winding arrangement has been established.
A percentage impedance needs context: the winding pair, reference power, tapping position and reference temperature applicable to the recorded result. Confirm that the value intended for marking agrees with the relevant final test record and the governing specification.
The guaranteed design value and the measured FAT value are not automatically interchangeable. A difference should be assessed against the agreed acceptance requirements; it should not be removed by copying the tender figure onto the plate. For three-winding units, make sure the reviewer is comparing the same winding pair and power base.
A statement such as “±2 × 2.5%” is not enough to verify the complete operating information. Check which winding is tapped, the principal tap, all position numbers, the voltage assigned to each position and the type of tap changer. Then compare the plate with the approved tapping diagram, the position indicator and the ratio-test record.
Illustrative example: assume an 11/0.4 kV transformer with five HV tapping positions at +5%, +2.5%, nominal, −2.5% and −5%. Assume the approved drawing assigns position 1 to the highest HV tapping voltage. This numbering is an example only; the actual manufacturer's approved schedule determines the sequence.
Example position | HV tapping designation | Assigned HV tapping voltage | Corresponding rated LV voltage |
|---|---|---|---|
1 | +5% | 11.550 kV | 0.400 kV |
2 | +2.5% | 11.275 kV | 0.400 kV |
3 | Principal tap | 11.000 kV | 0.400 kV |
4 | −2.5% | 10.725 kV | 0.400 kV |
5 | −5% | 10.450 kV | 0.400 kV |
The LV column refers to the corresponding assigned HV tapping voltage. It does not mean the secondary stays at 0.400 kV when a fixed 11 kV supply is applied at every position. Likewise, “+5%” on the HV tapping schedule should not be read as an instruction to raise the LV output by 5%. The approved winding arrangement determines the relationship.
If the plate lists these voltages in the opposite order from the approved indicator schedule, resolve the position mapping before shipment. Ask the factory to identify each position in the ratio-test record. A voltage list with no position reference leaves the receiving team to guess.
Distinguish an off-circuit or de-energized tap changer from an on-load tap changer. A nameplate review is not authorization to operate the mechanism: follow the manufacturer's operating procedure and isolation requirements. For an OLTC, check that the main plate, separate changer identification and approved control indication use consistent references.
The following examples are hypothetical inspection findings. They show why a nameplate discrepancy should be investigated before anyone requests a new engraving.
Finding | What to establish | Appropriate next step |
|---|---|---|
The final digit of the serial number differs from the FAT report. | Whether the report, fitted plate or assigned unit identity is wrong. | Hold release until the physical unit is positively linked to its records; then correct the identified error. |
The plate shows only the forced-cooling capacity. | The approved cooling-stage ratings and installed cooling arrangement. | Correct incomplete marking once engineering confirms the supported ratings. |
Tap positions run in the opposite order from the approved schedule. | The actual position-to-connection mapping and recorded ratio results. | Reconcile the indicator, drawing and plate; repeat affected checks where necessary. |
The marked impedance differs from the test report. | Winding pair, power base, tap, temperature and whether each figure is guaranteed or measured. | Obtain engineering disposition before changing the marked value. |
The marked total mass differs from the shipping list. | Whether one figure is the complete assembled mass and the other the transport configuration. | Clarify the configurations against final drawings and shipping records; do not assume either figure is a typing error. |
A plate-only correction is justified when the approved design, actual equipment and test evidence agree, and the error is confined to the marking. If those three sources disagree, keep the affected release item open. A replacement plate cannot establish an unknown winding connection or validate an unverified cooling rating.
Match the permanent serial number to the identifier inside the FAT reports, not just their filenames. Also check the final data sheet, dispatch list and any post-test rework record. Two units with identical ratings still need individual identification; a batch-level photograph is not enough to establish which unit was checked.
Keep the manufacturer's serial number separate from the purchaser's asset tag and the contract number. All three may be useful, but they serve different purposes. Where accessories travel separately, the packing references should identify the parent transformer without replacing the accessory's own identification.
For the recordkeeping method behind this check, see transformer factory traceability records. The nameplate review itself can remain compact: one photograph, a completed comparison record and the evidence closing any discrepancy.
Legibility: read every character, decimal point and unit on the installed plate; check that a photograph captures the complete information.
Attachment and access: confirm that the plate is securely fitted and remains readable in the final installation arrangement.
Liquid and mass information: reconcile marked quantities and units with the specified liquid and relevant final configuration.
Language and utility markings: check any required translation, asset number or purchaser format against the approved layout.
Replacement control: if a plate was changed, retain the discrepancy record, approved correction and photograph of the replacement fitted to the same unit.
The release reviewer should be able to identify who checked the plate, which drawing revision was used and whether any item remains unresolved. Avoid a single “nameplate OK” tick with no serial number or supporting photograph.
No. Drawing approval and physical inspection are separate checks. The fitted plate still needs to be compared with the approved layout and the actual unit's final records.
No. A confirmed engraving error may need controlled plate replacement and reinspection. If the discrepancy raises a question about the manufactured equipment or the validity of a test record, engineering must define the additional checks. The correction scope follows the cause.
No. Its data helps the review, but compatibility also requires an engineering assessment of the intended units and operating conditions. Matching nominal voltage and capacity alone is insufficient.
For a Zisheng Electric 132 kV–138 kV power transformer or oil-immersed transformer enquiry, send the approved data sheet, proposed nameplate drawing and tapping schedule. For equipment approaching dispatch, add the serial number, a legible photograph of the fitted plate and the relevant FAT pages. Identify any purchaser-specific marking format and the exact value that needs clarification.
This gives the engineering team a defined question to resolve before shipment: what should be marked, what is fitted, and what evidence confirms that they agree?
