Why is a generic THD column ambiguous?
The cited Galaxy VL IEC specifications place THDI at the input terminals of a single UPS and THDU at its output terminals. The output entry also distinguishes linear and non-linear load conditions. These are product-specific statements, not universal limits for every UPS or the whole facility.
Critical Power Drafting is independent and is not affiliated with Schneider Electric. Preserve the source terminology, including THDU where the manufacturer uses U for voltage. The design engineer decides the applicable project criteria and any power-quality assessment.
Sources: Schneider Electric: Galaxy VL IEC technical specifications, document 990-91377K-001
Which fields make the schedule reviewable?
Keep the specified limit separate from any measured result. A datasheet for one operating configuration should not silently become a site measurement or a guarantee at a common upstream bus.
| Field | Evidence | Review |
|---|---|---|
| Quantity | Current THDI or voltage THDU | Retain the actual source label |
| Location | Input, output and exact terminals | Single UPS or common bus |
| Condition | Load type, level and operating mode | Do not drop source qualifications |
| Value | Limit or observation with unit | Keep comparison operators |
| Reference | Product, document and revision | Match the selected configuration |
| Approval | Engineering review and disposition | No generic compliance claim |
What does an invalid comparison look like?
Illustrative example. A fictional drawing schedule has a field for output voltage distortion under a stated non-linear load. Its only reference is an input current distortion entry at full load. Even if both entries say percent, the reference does not answer the scheduled output-voltage question.
The drafter marks the evidence mismatch open and requests the approved output specification. Neither a smaller percentage nor a matching number resolves a different electrical quantity, location or load condition. This example supplies no real rating, pass threshold or harmonic calculation.
What changes when a UPS is added in parallel?
Retain the individual-unit reference and ask the engineer whether the common-system drawing needs different evidence. Do not copy an individual terminal claim onto a shared supply point without approval. Link the resolved note to the approved power-quality study or equipment data where required.
This worksheet does not select filters, change protection or authorize testing. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Are THDI and THDU interchangeable percentages?
No. They describe different quantities and require their own boundaries and conditions.
Does a product specification prove a site measurement?
No. Record measured evidence separately.
Can a single-unit claim be copied to a common bus?
Only with the responsible engineer's approved supporting basis.
Primary sources
- Galaxy VL IEC technical specifications, document 990-91377K-001Schneider Electric