Prepare diesel generator RFQs with alternator and motor-starting details, including inrush current, voltage dip, starting method, load steps, and site documents.
What buyers should know first
Motor starting is one of the main reasons a diesel generator that looks large enough on running load can still perform poorly on site. Pumps, compressors, crushers, fans, chillers, and hoists may draw high starting current. The alternator, excitation system, engine response, and start sequence should be reviewed together.
For Yangzhou Tesla Power Equipment Co., Ltd. to quote the package correctly, send the project load data, installation conditions, and electrical boundary requirements together rather than separating them across several messages.
In practice
A purchaser should not rely only on total motor kW. The starting method matters: direct-on-line, star-delta, soft starter, and variable frequency drive loads can lead to different voltage dip and recovery behavior. Send the motor list early so the supplier can discuss alternator sizing and load-step assumptions.
| Motor detail | RFQ input | Why it changes selection |
|---|---|---|
| Largest motor | kW, voltage, starting method, starting current if known | Sets the worst starting event |
| Start sequence | One at a time or simultaneous starting | Changes transient load on the generator |
| Sensitive loads | UPS, PLC, medical equipment, drives, controls | May need tighter voltage dip review |
| Duty cycle | Starts per hour and daily running hours | Affects thermal and operational assumptions |
What to confirm before quotation
- List each large motor with power, voltage, starting method, and operating duty.
- Mark which motors must start after utility failure and which can be delayed.
- State acceptable voltage dip if the project has a requirement.
- Confirm whether an oversized alternator, staged starting, or soft starter is acceptable.
- Ask for the generator data sheet and any motor-starting review notes included with the offer.
Common configuration mistakes
- Adding motor nameplates together without checking simultaneous operation.
- Ignoring the difference between direct-on-line and soft-start loads.
- Selecting by standby kVA when the generator will support repeated motor starts.
- Not telling the supplier about UPS or control loads that may trip during voltage dip.
Internal references for specification work
Start with industrial diesel generator sizing guidance, then compare operating use with prime and standby rating notes. For factory installation details, see ventilation checks before RFQ. A related product example is Cummins Engine 6BTA5.9-G2 100kw to 400kw Diesel Generators with ATS 125kva to 500kva Power GenSet 230v & 240v Rated Voltage.
Documents to request with the offer
- Motor list
- Starting method details
- Load sequence
- Voltage dip requirement
- Site single-line diagram
- Generator technical data sheet
Questions purchasers often ask
Does a larger alternator always solve motor starting?
Not always. It can help, but engine response, starting method, load sequence, and acceptable voltage dip also matter.
Should motors be started one by one?
Often yes for generator-fed systems. Staged starting can reduce the required generator and alternator size.
Can VFD loads make sizing easier?
They may reduce starting current, but harmonics, input configuration, and bypass operation should still be checked.
What if starting current is unknown?
Send motor nameplate photos, starting method, and equipment type. The supplier can discuss assumptions, but final design should be checked by the project engineer.
Before sending an RFQ, prepare the connected load list, operating voltage, frequency, duty rating, installation layout, ambient conditions, fuel autonomy target, and any electrical boundary drawings. Clear inputs help the supplier quote the generator set instead of guessing the project scope.