Classify single- and three-phase load requirements, compare exact-build output evidence, and return incomplete generator quotations before order.

Choose a single-phase or three-phase direction from the site's electrical needs and controlled load list, then require the exact quoted set to show where it delivers that output and under which limits. Return an offer when supplier records omit or contradict the connection, line-to-line or line-to-neutral basis, or build identity; hold the choice when the project input itself needs qualified electrical review. This quotation-control method does not design wiring, protection, grounding, transfer equipment, or the site electrical system.

Start with required connections, not the phase label

“Single phase” and “three phase” are not complete buying terms. Start with what each main load needs at the point of use.

Freeze the destination basis before comparing generators:

  • Destination market and project location.
  • Required frequency.
  • Required voltage or voltages, with each value marked as line-to-line, line-to-neutral, or another project-defined reading.
  • Phase need stated by the project or equipment document.
  • Neutral and wire need, if the project documents define one.
  • Operating groups, load order, and loads that must remain available together.
  • the controlled source for each entry: equipment datasheet, tender, approved load schedule, site drawing or qualified designer.

A voltage number alone does not define the phase. It also says nothing about the supplied connection or the power available through it. Use the generator voltage and frequency checklist to record the site's needs before comparing offers.

Build the load list without guessing at missing electrical data:

Load field Buyer record Completion rule
Load identity Equipment description, model or controlled tag; quantity The same load can be found in its source document.
Supply requirement Stated phase, voltage, frequency and connection need Unknown values remain OPEN; a familiar equipment name is not a substitute.
Connection category Explicit single phase, explicit three phase, line-to-line, line-to-neutral or unclear The category comes from a controlled requirement, not from the buyer's assumption.
Operating role Operating group, sequence, criticality and known transient or sensitive behaviour The commercial review can see which loads may operate together.
Evidence source File title, identifier and revision Every material requirement is traceable.
Review status Buyer-defined, supplier input needed or qualified review required Unresolved items stay visible before quotation comparison.

Some equipment needs more than the right phase label. A UPS, VFD, or other nonlinear load may also have power-quality or short-term response needs. Record those needs on a separate path; the guide to generator inputs for UPS, VFD and nonlinear loads explains the handoff. Do not bury them in one total-kW line.

Turn the load schedule into a phase direction

The load list sets the direction of the request. It is not an electrical design. Group the known needs first, then state what the supplier must prove.

Keep five categories visible

Category What it means for procurement What it does not prove
Explicit single-phase load The controlling equipment or project record states a single-phase supply requirement. That any single-phase outlet or terminal on any set can serve it.
Explicit three-phase load The controlling record states a three-phase supply requirement. That a generic three-phase generator matches the required voltage, connection or load behaviour.
Line-to-line requirement The record names a supply measured between lines. That the phase label alone proves the required value is available.
Line-to-neutral requirement The record names a supply measured between a line and neutral. That the offered set has the required neutral or usable output for this load.
Unclear / qualified review A material requirement or its source is missing, conflicting or open to design interpretation. Any safe phase choice.

One load may have more than one stated need. Record each one instead of forcing the load into a convenient column. This step does not work out current, diversity, motor starting, cable size, or phase balance.

Write one controlled direction statement

Use one of four outcomes:

  • Single-phase direction: the material load records support a single-phase request, and no documented three-phase or unresolved connection requirement changes that request.
  • Three-phase direction: the material load records include a defined three-phase requirement, while other material connection needs and the destination basis are also known.
  • Mixed-output direction: the schedule contains documented requirements that must be evaluated across more than one output type, such as line-to-line and line-to-neutral loads.
  • No direction yet: a material load, frequency, voltage, phase, connection or neutral requirement remains unresolved.

These statements only route the RFQ. They do not prove that a set is suitable. For a mixed load list, ask for the exact output layout and usable power at each needed connection. Also ask for the supplier's load-sharing limits and list any open design questions.

Make the supplier declare the exact offered output

A product family, base model, or “single/three phase” label cannot close the review. Similar names may hide different alternator links, controllers, panels, or market versions. Put each option on its own quote row. Ask for a return tied to that exact build.

Rows of enclosed generator sets with front control panels and large covered connectors visible
The visible connectors and panels are configuration features to document. They do not establish phase, winding connection, neutral availability, simultaneous outputs, rated capacity, protection or the exact configuration offered.
Return block Supplier response required for the quoted build
Commercial identity Quotation number, date, revision, line item and exact set/configuration code.
Destination basis Offered voltage, frequency and phase, each matched to the buyer's stated destination requirement.
Output arrangement Alternator winding/connection declaration; line-to-line and line-to-neutral outputs where relevant; neutral/wire availability as stated for the build.
Rating basis Rated kW, rated kVA, rating designation, stated power-factor basis and the conditions attached to those declarations.
Usable output Output available by each connection or interface required by the project, including any supplier-stated shared or configuration limits.
Phase-specific data Per-phase current or rating where relevant and the supplier's stated load-distribution or imbalance basis. Do not insert a universal threshold.
Protection and interface Declared output path, protection/interface identity and limits. Connector or panel SKU selection remains a separate task.
Controls Controller identity and the metering or protective functions being offered, without inferring unlisted functions.
Package identity Engine, alternator, controller, output configuration and set/build identifiers.
Evidence Revised quotation, configuration datasheet, controlled nameplate record or photo, output-connection diagram and applicable test/report reference.
Change control Assumptions, exclusions, optional items, permitted substitutions and changes that require revised evidence.

“Dual voltage,” “reconnectable,” or “single/three phase” may name a family of options. It may not describe the set as shipped. The supplier must state the quoted state and the output available in that state. Do not assume that all listed outputs work at once, use the supplied panel, or share one rating.

Treat alternator data the same way. It may help, but it does not prove the output of the full set through the offered panel or terminals. The ISO catalogue lists separate scopes for AC generators used in generating sets, set ratings and performance, and set test methods.

These catalogue pages do not prove product compliance. They also do not show that a supplier report covers the quoted build.

ISO 8528-3 scope page describing alternating-current generators used in generating-set applications
ISO 8528-3 catalogue scope captured from ISO on September 2, 2026. It separates an AC-generator component scope from the wider generating-set decision; it is not product compliance evidence or a universal phase-selection rule.

Use the Phase Configuration & Output Evidence Matrix

Create one row for each offered build. Never put two options in one cell, even if they share a supplier or enclosure.

Matrix field Evidence to record Decision question
Quote identity Quote, line, revision and date Is this the exact commercial alternative being compared?
Project direction Single-phase, three-phase, mixed-output or no direction; list open loads Is the buyer requirement defined enough to compare?
Offered electrical basis Phase, voltage, frequency and stated connection arrangement Does the offer answer the same requirement?
Required outputs Required line-to-line and line-to-neutral paths; stated neutral/wire need Are all material load connections addressed?
Rating declaration kW, kVA, rating designation and power-factor basis Are headline values being compared on the same declared basis?
Usable-output return Output by required offered connection and associated limits Does the supplier prove what the package can actually deliver where needed?
Per-phase / distribution return Applicable per-phase data and supplier-stated distribution basis Are material distribution conditions visible rather than assumed?
Build identity Engine, alternator, controller, set and output-panel/configuration codes Do the records describe one build?
Document set Quotation, datasheet, plate record, diagram and test/report title/revision Can every material declaration be traced?
Exceptions and change control Open points, exclusions, optional items and substitution rules Would a change invalidate the comparison?
Status COMPARE, RETURN or HOLD, plus owner and reason What happens next?

Apply the states consistently:

Matrix routing buyer phase requirements and supplier output evidence into compare, return, or hold states
Use the matrix to control procurement progress. A COMPARE state means the quotation bases align; it does not approve wiring, protection, installation, or project suitability.
  • COMPARE when the project inputs are defined, required supplier fields are complete, critical records describe the same build, and no material review issue is hidden.
  • RETURN when the project requirement is defined but the supplier controls a missing, generic or inconsistent field. Send back the named gaps rather than interpreting them for the supplier.
  • HOLD when a material project input is unknown, the offered arrangement conflicts with the requirement, configuration identity cannot be reconciled, or qualified review remains necessary. Do not release the order.

A clear single-phase load list may reach COMPARE when the exact-build records agree. A generic “three phase” brochure cannot answer a mixed-output list; mark it RETURN. Use HOLD when a main load has no confirmed supply need. Also use it when the diagram and nameplate show different output layouts.

When the supplier will change the alternator connection, controller, panel, outlets, labels, or manuals for the destination version, attach the phase-and-load record to the BEAR OEM and private-label project review.

The status controls procurement progress. It is not engineering approval.

Reconcile the documents and the unit offered

Evidence only helps when its subject and revision are clear. Match the model and build code across the quote, data sheet, plate record, output diagram, and test reference. If a code differs for a valid reason, ask the supplier to explain the link and its scope in writing.

The pre-order generator document checklist gives the wider file-control method. For this phase decision, pay particular attention to five breaks:

  1. Family evidence, not exact-build evidence: a catalogue covers several phase or voltage options but does not name the quoted one.

  2. Part evidence, not package evidence: an alternator sheet is used as proof of set output without the supplied connection, panel, and protection scope.

  3. Revision conflict: the quote, drawing, plate record, or report belongs to a different build.

  4. Open option control: a part or connection may change after comparison without a new supplier return.

  5. Test scope mismatch: the report does not name the right set, test conditions, output layout, or measured points.

Before sample or production approval, record the unit or build used for the check. Match its plate, controller, output layout, and diagram to the approved quote line. A traceable photo can support identity. An unknown photo cannot prove the build, and a verbal answer cannot close a document conflict.

Reopen the matrix after any change to the alternator, winding link, controller, output layout, protection, interface, or rating. The old COMPARE state no longer applies. Review the new records first.

Reject the shortcuts that make quotations look comparable

Neither phase is a universal winner. The right request depends on the known loads and site system. The right quote depends on what the exact offered build can deliver.

Return or hold an offer when it relies on any of these shortcuts:

  • A voltage number is used as proof of phase.
  • “Industrial,” “commercial,” or “residential” replaces the load list.
  • A fixed kW cutoff is used to choose phase.
  • Total kW or kVA is compared without the rating and power-factor basis.
  • “Three phase” is treated as proof of every needed line-to-neutral output.
  • “Single/three phase” or “dual voltage” is not split into exact options.
  • An unstated phase-balance rule or universal imbalance rate is assumed.
  • Product-family data is mixed with an exact-build quote.
  • Alternator capability is treated as usable packaged output.
  • The test report, diagram, or plate belongs to another build.
  • An unapproved part change is allowed after comparison.
  • price, fuel use, efficiency, durability or maintenance is attributed to phase alone.

These are not small paperwork gaps. A shortcut can change the loads served, the power available, or the meaning of a quoted rating. Stop when the answer depends on design, law, installation, or safety. Send that question to the qualified project and electrical reviewers, not to a generic online guide.

Send one RFQ and evidence packet

Send every supplier the same controlled input. You can then compare returns without rebuilding a long email trail.

Buyer input

  • Destination market and project location.
  • Use and operating case.
  • Required voltage or voltages and how each is defined.
  • Required frequency.
  • Project-stated phase and connection needs.
  • Attached load list with single-phase, three-phase, line-to-line, line-to-neutral, and open items marked.
  • Neutral and wire need if stated by the project.
  • Loads or design questions that need qualified review.
  • quantity and any commercial variant that changes the technical build.

Supplier return

  • Exact quote, revision, line item, and set configuration code.
  • Engine, alternator, controller, and output-build identity.
  • Offered phase, voltage, frequency, winding link, and stated neutral or wire availability.
  • Rated kW and kVA, rating name, and stated power-factor basis.
  • Usable output through each connection the project needs.
  • Per-phase current or rating where needed, plus the supplier's load-sharing or imbalance basis.
  • Protection, interface, controller, and meter details within the offer.
  • Exact-build data sheet, plate record or clear traceable photo, output diagram, and relevant test references.
  • Written assumptions, exclusions, options, and change-control terms.
  • an explanation for every difference among the quotation, datasheet, plate, diagram and report.

For a BEAR enquiry, send Miya the site basis, grouped load list, quantity, and required return fields. Keep the request open until BEAR names an exact offered build and returns records for it. A brand name, phase label, or product family is not a promise of supply or fit.