What buyers should know first
UPS systems, VFDs, soft starters, rectifiers, and other nonlinear loads can affect generator voltage waveform, alternator heating, and control stability. A generator sized only by total kW may still need review when the load mix has high harmonic content.
For an accurate quotation, provide the load list by equipment type. Yangzhou Tesla Power Equipment Co., Ltd. can then discuss alternator sizing, AVR requirements, motor starting assumptions, and whether a specialist harmonic study is needed.
Load information to collect
- UPS capacity, input type, rectifier technology, and charging mode.
- VFD motor size, number of drives, and whether bypass operation is required.
- Large rectifier, charger, welder, or electronic load details.
- Expected step loading sequence and allowable voltage dip.
- Any harmonic limits stated by the project consultant.
Where RFQs become unclear
- The buyer sends only total facility kW, without separating motors, UPS, HVAC, lighting, and electronic loads.
- UPS recharge current after an outage is ignored, so the generator sees more load than expected.
- The project asks for a smaller generator but also expects tight voltage stability under mixed nonlinear loads.
Checklist table
| Load type | Detail to confirm | Why it matters |
|---|---|---|
| UPS | kVA, rectifier type, recharge current | Can affect harmonic content and step load |
| VFD | Motor kW and operating sequence | Affects starting and running current profile |
| Rectifier load | Quantity and duty cycle | May require alternator review |
| Critical load | Voltage dip tolerance | Guides sizing and control settings |
Before requesting a quotation
Share the single-line diagram, load schedule, UPS and VFD data sheets, required voltage and frequency, and the acceptable voltage dip during load steps. Ask for alternator data and written assumptions used for sizing.
Questions purchasers often ask
Can a diesel generator run UPS and VFD loads?
Yes, but the generator and alternator should be reviewed against the actual load mix, step loading, and harmonic conditions.
Is total kW enough for quotation?
Total kW is a starting point, not the full answer. Nonlinear load type, starting sequence, and voltage dip tolerance should also be provided.
Does a larger alternator help?
It may help in some cases, but the correct choice depends on the load profile, AVR performance, harmonic limits, and project acceptance criteria.
What should be checked during commissioning?
Check voltage stability, frequency recovery, UPS transfer behavior, VFD operation, alarms, and load-step performance under realistic site conditions.
RFQ notes to include
For a clearer quotation, send the site country, voltage and frequency, duty rating, load list, installation layout, control interface requirements, noise or enclosure expectations, and any drawings already approved by the project engineer. Ask the supplier to state assumptions in writing so commercial comparison is based on the same scope.