Transformer loss capitalization compares the bid price with the evaluated cost of no-load and load losses. For liquid-immersed distribution-transformer procurement, use the purchaser’s approved loss factors, consistent guaranteed loss values, and the same commercial scope across offers. The lowest calculated total is meaningful only after technical requirements and the applicable approval path are satisfied. It is an evaluation result, not a guaranteed electricity bill or a substitute for engineering acceptance.
This guide is for U.S. utility procurement teams and engineers preparing or reviewing transformer bids. It focuses on the loss-evaluation worksheet, rather than general quotation terms or transformer sizing.
Transformer loss capitalization formula and units
A common calculation is:
Evaluated cost = comparable bid price + A × no-load loss + B × load loss.
- A: the purchaser’s capitalized value of no-load losses, expressed here in USD/W.
- B: the purchaser’s capitalized value of load losses, also in USD/W.
- No-load loss: the specified loss in watts under the agreed voltage, frequency, tap and reference conditions.
- Load loss: the specified loss in watts at rated load and the agreed reference conditions.
The USDA Rural Utilities Service economic-evaluation guide describes this purchase-price-plus-losses approach. Its guidance is not itself a binding procurement requirement. The owner’s approved methodology and tender documents determine the evaluation used for the purchase.
Label the result clearly. A worksheet containing price and capitalized losses does not automatically include every installation, maintenance, removal or other lifecycle cost. Show additional included costs separately and avoid counting any item twice.
Who should set the A and B factors?
The purchaser should establish the evaluation factors and issue the same factors to all bidders. Ask the utility’s engineering and economic-analysis teams to approve their derivation, rather than copying a value from an online example.
Bonneville Power Administration’s distribution-transformer research explains that loss valuations depend on matters such as loading, operating hours, energy costs and financing assumptions. The factors therefore belong to the buyer’s intended operation and economic basis; they are not fixed characteristics of a transformer.
Record the factor owner, approval date, currency, units, evaluation period and assumptions reference. If different service groups require different factors, identify those groups before bidding. A continuously energized service and a seasonal service should not inherit the same assumptions without review.
Keep sensitivity analysis separate from the award basis. Procurement should be able to identify which calculation uses the issued tender factors and which explores a different future scenario.
Which loss values can be compared?
Compare loss values only when their rating and reference basis match the specification. Ask each bidder to complete a short loss schedule alongside the offered design reference:
- Rated kVA, primary and secondary voltages, phase and 60 Hz frequency
- No-load loss and load loss in clearly stated W or kW
- Voltage, current or loading basis, tap position and reference temperature
- Test method, guarantee status, and the applicable tolerance or acceptance provisions
- Cooling arrangement and any auxiliary power included or excluded
UNEP’s transformer procurement guide distinguishes no-load and rated-current load losses and includes cooling power where relevant. Do not apply a simplified passive-cooling calculation to an offer with auxiliary consumption that the evaluation ignores.
A brochure efficiency percentage alone does not populate this schedule. Likewise, an estimated loss is not automatically equivalent to a guaranteed value. Mark missing or differently defined values as unresolved and request clarification before ranking the bids.
A worked example: when a lower-loss offer still costs more
The following numbers are fictional worksheet inputs, not HEAKOR prices, product specifications or recommended utility factors. Assume two technically acceptable offers have already been placed on the same delivery and test scope.
- Offer 1: USD 4,800 price; 120 W no-load loss; 600 W load loss.
- Offer 2: USD 5,250 price; 80 W no-load loss; 500 W load loss.
- Illustrative factors: A = USD 6/W and B = USD 2/W.
Offer 1 evaluates to 4,800 + (6 × 120) + (2 × 600) = USD 6,720. Offer 2 evaluates to 5,250 + (6 × 80) + (2 × 500) = USD 6,730.
Offer 2 has lower losses, but its USD 450 price premium exceeds the USD 440 evaluated reduction in loss cost. Under these inputs, Offer 1 is lower by USD 10. This does not establish a universal preference for either design.
For a separate sensitivity case, change A to USD 8/W while keeping B unchanged. The evaluated totals become USD 6,960 and USD 6,890 respectively. Offer 2 is then lower by USD 70. The reversal shows why the approved factor basis matters; it does not authorize changing tender factors after seeing the bids.
Five checks before issuing the recommendation
- Check units. Multiply USD/W by W, or USD/kW by kW. Mixing the two introduces a thousandfold error in that term.
- Check scope. Use one agreed price basis and identify exclusions before comparing totals.
- Check eligibility. A favorable evaluated cost does not prove product-standard compliance, required certification or utility acceptance.
- Check the evidence trail. Record the bid revision, offered design, guaranteed schedule and calculation revision.
- Check acceptance treatment. Agree how test results will be assessed against the guarantees and what happens if they differ. Do not invent an automatic penalty or acceptance rule.
For covered U.S. equipment, verify the applicable efficiency, testing and certification requirements independently using the Department of Energy’s distribution-transformer resources. The economic comparison cannot establish regulatory coverage or compliance. Use the U.S. buyer checklist for the broader approval review.
Keep the bid comparison in one worksheet
| Input or result | Offer 1 | Offer 2 |
|---|---|---|
| Comparable price (USD) | 4,800 | 5,250 |
| No-load loss (W) | 120 | 80 |
| Load loss (W) | 600 | 500 |
| Evaluated cost at A = 6 USD/W, B = 2 USD/W | 6,720 USD | 6,730 USD |
| Separate sensitivity: A = 8 USD/W, B = 2 USD/W | 6,960 USD | 6,890 USD |
Before sending the loss schedule to HEAKOR, use the transformer RFQ checklist to align ratings, test scope and delivery terms. Do not rank an offer with unresolved technical deviations as equivalent to an accepted design.
For the wider evidence request, review the project technical documents and identify the records required before approval.
Frequently asked questions
Is the evaluated cost the amount paid to the supplier?
No. Capitalized losses are an evaluation allowance, not automatically a supplier invoice item. Keep the contract price, evaluation adjustments and any agreed performance remedies separately identified.
Can the same A and B factors be used for every project?
Only if the purchaser has approved that common basis for those applications. Different operating assumptions can require a different evaluation. Record the justification rather than assuming a previous project’s factors remain suitable.
Should annual energy cost be added again after capitalizing losses?
Do not add the same loss cost twice. Ask the model owner which operating costs the factors already capture and add only separately justified items outside that scope.
What if the two evaluated totals are nearly equal?
Show the small difference and the assumptions affecting it. Keep technical acceptance and the tender’s other award criteria visible; a narrow numerical lead should not conceal an unresolved requirement.
Can measured losses replace the bid guarantees?
Only under the agreed procurement and acceptance procedure. Identify the tested unit and reference conditions, then have the responsible reviewers apply the contract’s provisions. A later test result should not silently overwrite the original evaluation record.
Prepare a loss-evaluation enquiry
For an oil-immersed transformer enquiry to HEAKOR, include the electrical specification, destination, purchaser-approved A and B factors, loss-reference basis, required guarantees and tests, quantity and delivery scope. Request an offered-design response identifying losses, deviations and unresolved requirements. Suitability for a U.S. utility project and its approval requirements must be confirmed for the specific proposal.