Prepare an industrial generator RFQ with controlled load data, start events, site conditions, rating basis and comparable supplier evidence.
Do not size an industrial generator from one connected-load total. Send each supplier the same load list, run scenarios, worst credible start or load step, site data and rating basis. This input pack supports a qualified application review; it does not select the set or approve the system design.
Build a controlled load list
A usable load list keeps a separate record for each load. Leave missing values open. Label data from a nameplate, a measurement or an estimate so the supplier can tell them apart.
Use one row per load or controlled group:
| Field. | What to record. |
|---|---|
| Identity. | Record the load tag, equipment description, quantity and data revision. |
| Electrical basis. | Record voltage, frequency, phase, running current, kW, kVA and power factor where available. |
| Data source. | Name the nameplate, manufacturer document, design schedule, measurement or estimate. |
| Operating role. | Mark it as essential, optional, delayed, shed-able, intermittent or mutually exclusive. |
| Start behavior. | Record starting current or kVA where provided, plus the starter method and expected duration. |
| Control owner. | Name who confirms whether the load may run, start, stop or be shed in each scenario. |
Keep unknown fields visibly open. A supplier can investigate a missing motor value. But after a guess and a measured value are pasted into the same total, it cannot tell which is which.
A sizing tool still needs the buyer to define the load types, quantities, start methods and run pattern. Its result does not by itself select a BEAR model or prove that the chosen scenario matches the site.
Define operating scenarios before adding demand
Connected load and simultaneous demand answer different questions. Create named scenarios. Show which loads are online together and which may start during that state. Also name each load that is delayed or shed.
A small scenario register is enough:
| Scenario. | Loads already online. | Event. | Delayed or shed. | Evidence owner. |
|---|---|---|---|---|
| Normal operation. | Use a controlled list of running loads. | Record expected cycling. | Name optional loads. | Assign the site operator. |
| Highest credible running state. | Record the maximum permitted combination. | State the event, or state that there is none. | Name mutually exclusive loads. | Assign the project engineer. |
| Start or transfer state. | List the loads retained during the event. | Define the motor start, block load or staged loads. | Define the sequence. | Assign the controls designer. |
| Future state. | List approved expansion loads. | State the future step. | Name loads outside the scope. | Assign the buyer. |
Do not apply a generic diversity factor just because two loads seem unlikely to overlap. The run plan, transfer logic or load controls must support that claim. The buyer must define normal use, start events and load order; a stock sizing rule cannot supply those inputs.
Preserve kW, kVA and power factor without defaults
Real power in kW and apparent power in kVA describe different constraints. Where the values share the same measurement or rating basis, power factor is PF = kW / kVA. Keep the original kW, kVA and PF by load when the evidence provides them.
Fluke's power-factor reference defines PF as the ratio of working power in kW to apparent power in kVA. That identity does not justify a default PF for an unknown load. It also does not make the declared PF on a generator rating the same as the facility's load PF.
For every calculated field, record:
- the source inputs and units.
- whether the value is measured, declared or estimated.
- the load condition and configuration.
- the person responsible for accepting the assumption.
If a supplier converts the whole schedule with one assumed PF, ask for the original per-load values. Also ask which assumptions the conversion affected. Use the rated-versus-peak power guide to reconcile rating labels and declared output. This article only controls the sizing inputs.
Describe the worst credible start or load step
Starting kVA is not a complete acceptance requirement. Describe the event and the loads already online. State the actual starting method. Then record the voltage or frequency disturbance and recovery that the connected equipment can accept.
For a significant motor or block load, return these fields:
| Event field. | Required input. |
|---|---|
| Equipment. | Give the motor or load tag and controlled equipment data. |
| Starting data. | Give starting current, locked-rotor kVA or other manufacturer data where available. |
| Start method. | State across-the-line, reduced-voltage, soft starter, VFD or the exact project method. |
| Pre-event state. | List the loads already online and the generator operating condition. |
| Sequence. | State what starts first, any delay or overlap, and what must remain energized. |
| Acceptance basis. | Give the permitted voltage or frequency disturbance, recovery criterion and source. |
| Supplier proof. | Give a calculation, sizing-software report, curve or test reference tied to the offered configuration. |
There is no one starting-current multiplier or voltage-dip limit for every project. A named start method, disturbance limit and load sequence are inputs, not proof that the load will start. The application reviewer must check the exact offered set against the connected equipment's limits.
Use the voltage and frequency checklist when the project still lacks a controlled output configuration. Cable sizing, protection, grounding, ATS design and installation remain outside this article.
Record site and rating conditions
Ask for the rating available at the stated site, not only the catalogue headline. Record the operating duty, project voltage and frequency, altitude and ambient range. Also record the fuel, enclosure or room arrangement and airflow constraints. Add any other site input required by the manufacturer.
The official ISO 8528-1:2018 catalogue record covers classifications for generating-set application, rating and performance. The catalogue page does not prove supplier conformity or prescribe this RFQ form.
Product documents show why the exact rating basis matters. The dated mtu 6R0225 DS400 product sheet is revision 231118 / 2024-08. It states its own reference conditions. It also directs readers to obtain product-specific altitude and temperature deratings.
This is one manufacturer's product document. It only shows the type of rating and derating information a buyer should request. It is not a BEAR rating or a universal derating chart.
Ask each supplier to state:
- the duty and rating definition used.
- the standard or reference conditions behind the headline rating.
- the output available at the buyer's stated conditions.
- the engine, alternator, control and enclosure configuration used in the review.
- every derating, assumption and exclusion.
- the document or calculation revision.
Compare supplier responses on one evidence matrix
Headline kVA is comparable only after the input and evidence basis matches. Give every supplier the same load scenarios, start event and site conditions. Then compare their returns against the same rating duty and revision.
Use four response states for every field designated by the buyer or project specification. This matrix controls supplier returns; it is not an ISO form, engineering calculation, acceptance test, or final selection tool.
CONFIRMED: the supplier gives a configuration-specific response tied to stated conditions and a supporting document or reference. It does not mean suitability has been independently established.CONDITIONAL: the value depends on a stated assumption or pending project input.NOT OFFERED: the proposed configuration does not meet that field.OPEN: the supplier has not supplied enough evidence to decide.
When supplier-selected controls, enclosure, cooling, or electrical options change a sizing input, carry the completed load, event, and site matrix into the BEAR OEM and private-label project review.
Each return must name its reviewer, calculation or test reference, assumptions, exclusions and revision. The generator document checklist explains how to keep the quotation, data sheet, drawing, nameplate proposal and test files tied to the same build.
Send a controlled sizing brief
Send one revision-controlled package. It should contain the load list, scenario register, start-event record, site sheet and response matrix. Ask every supplier to mark deviations rather than silently changing the buyer's inputs.
Before the comparison starts, verify that:
- load identities and data sources are visible.
- operating scenarios name simultaneous, delayed and shed-able loads.
- kW, kVA and PF are preserved rather than replaced with a default.
- the worst credible start or load step has an acceptance basis.
- site and rating conditions match across offers.
- every supplier response names its assumptions, evidence and revision.
Critical, complex, regulated or site-specific projects need more review. Have qualified application and site engineering professionals check the final generator rating and system design. This guide does not perform that review. To organize a model review without assuming availability, send Miya the destination, application, controlled load schedule, voltage/frequency and estimated quantity.
