Read the operating conditions behind the label
Source-based explanationCaterpillar distinguishes backup ratings, prime operation with varying load, and continuous operation with a non-varying load. The paper attaches operating conditions to its categories; the headline output alone does not describe the permitted duty. [1]
Use & limitsThese are Cat’s published categories. They are not a translation table for every maker’s terms.
What to ask next
Editorial checklist
- Write expected hours per year and whether the generator is backup or the principal power source.
- Provide the expected load profile, including sustained demand and occasional peaks. Ask which published rating definition matches it.
Keep the original designation on the offer
Source-based explanationT-030 also separates standby, prime and continuous rating guidance. For purchasing, retain the maker’s designation and the offered complete-set output together. [2]
Use & limitsDo not derive one duty rating from another using a universal percentage.
What to ask next
Editorial checklist
- Request the exact model, kWe, kVA, rated power factor, frequency and voltage under the proposed duty.
- Record any operating-hour, average-load or overload restriction in the quotation rather than relying on a translated marketing label.
Turn ambiguity into a clarification request
Source-based explanationWhen two sellers use different category names, a useful comparison starts with the definitions they cite. Our editorial recommendation is to leave the duty field unresolved until the supplier provides that definition. [1]
Use & limitsA clear label still does not establish suitability for the actual load or installation.
What to ask next
Editorial checklist
- Ask: Which document and revision define this rating, and which operating limits apply?
- Keep the answer with the quote. Compare matched duty conditions before comparing price, and send the project load schedule for model-specific review.
How two makers label the same duties
Source-based explanationAGG publishes its AS250D6 with separate prime (225 kVA / 180 kW) and standby (250 kVA / 200 kW) figures at 60 Hz. Hosem publishes the A-SH550 with Rate Power (500 kVA / 400 kW) and Max. Power (550 kVA / 440 kW) labels at 50 Hz. The label sets are not interchangeable: match the offered unit against the maker's own definitions before comparing numbers across brands. [3][4]
Use & limitsLabel examples from two makers only; definitions differ by maker and are not a conversion rule.
What to ask next
Editorial checklist
- Copy the exact rating label from the datasheet into your RFQ.
- Ask each maker which of its labels matches your duty.
RESEARCH IN VIEWDecision framework
01
Define the briefOutput, duty and site conditions
02
Match the packageModel, components and delivery basis
03
Check the evidenceEntity, documents and test scope
04
Record the gapsClarify exceptions before comparing
Sources, dates and scope
4 references. Each record keeps its own review date. A manufacturer disclosure is not an independent test; a retrieval date is not a price-effective date. Hover, focus or tap a numbered reference to inspect its source.
- [1]Manufacturer technical paperwww.cat.com
Caterpillar · Generator Ratings: Prime, Standby Power and More ↗
Use & limits
Cat rating definitions; retain the named category and its conditions. Do not map every commercial label directly to an ISO designation.Sections Standby, Emergency Standby Power, Prime, Continuous
Publication date not stated · Web edition; publication date not stated · Reviewed 2026-10-22View the recorded evidence
Cat distinguishes backup duty, varying-load prime duty and constant-load continuous duty, with operating limits for each.
- [2]Manufacturer application manualwww.cummins.com
Cummins · Liquid-Cooled Generator Set Application Manual ↗
Use & limits
Application guidance for liquid-cooled sets; not a current model datasheet or a universal installation code. The 2024 upload path is not the edition date.Sections 2.2–2.6; chapter 3; section 4.5.5 (printed p.67); chapters 5–6
Published 2015-02 · T-030 · Issue 9 · February 2015 · Reviewed 2026-10-22View the recorded evidence
Covers power requirements, equipment selection and installation interfaces. Weather protection and acoustic housings serve different purposes.
- [3]Manufacturer disclosurewww.aggpower.com
AGG · AS250D6 60 Hz product specifications ↗
Use & limits
One generating-set model; not a test performed by ChinaManufacturer.Named source page / model table; see recorded evidence
Publication date not stated · Original public record · Reviewed 2026-10-19View the recorded evidence
AS250D6: 60 Hz, 1,800 rpm; standby 250 kVA/200 kW; prime 225 kVA/180 kW.
- [4]Manufacturer disclosurewww.hosempower.com
Hosem · commercial standby generator specifications ↗
Use & limits
A-SH550 table; preserve original labels Max. Power and Rate Power rather than silently equating them to ISO ratings.Named source page / model table; see recorded evidence
Publication date not stated · Original public record · Reviewed 2026-10-19View the recorded evidence
A-SH550: 50 Hz; Rate Power 500 kVA/400 kW; Max. Power 550 kVA/440 kW. Engine SDEC SC25G690D2.
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A useful correction