Image note: The representative photograph shows a rotary operating head. Its rear contact unit and Ue, Ui or Uimp ratings are not shown. It does not establish the complete configuration or electrical performance. Verify exact model marking, certificate scope and current documentation.
Ue vs Ui vs Uimp: identify the question behind the label
An enquiry that asks only for voltage can receive several technically different answers. The following comparison is a reading aid, not a product specification or an insulation-design method.
| Field | Meaning to retain | Evidence question |
|---|---|---|
| Ue | Rated operational voltage | Which circuit, current and operating duty does this statement cover? |
| Ui | Rated insulation voltage | Which insulation reference and product documentation apply? |
| Uimp | Rated impulse withstand voltage | What stated impulse capability belongs to this exact configuration? |
| Document context | Identity and conditions around the number | Does the quotation identify the same item and revision as the source? |
The useful comparison is between matching fields on matching configurations. A larger-looking number in a different field does not answer the original question. Avoid giving all three entries a shared spreadsheet heading such as maximum voltage.
What Ue tells the buyer
Schneider Electric's operational-voltage explanation relates Ue to operational current and utilisation category in its contactor context. This is why an isolated voltage figure is an incomplete description of switching duty.
For a purchasing comparison, retain the relevant table heading and the other entries in the same row. If the supplier sends only a cropped number, ask for the surrounding page and exact model reference. Do not silently combine the voltage from one row with a current found elsewhere.
Separate the component being switched from the component doing the switching. A control assembly may contain several separately documented functions. Ask which circuit a statement describes before treating it as a rating for the whole order. The panel-mount push-button buyer FAQ addresses the wider actuator, contact and interface configuration.
Why Ui is not another operating-voltage offer
Schneider's insulation-voltage explanation identifies Ui as a reference for dielectric tests and creepage distances. That label answers a different question from Ue. It does not, by itself, authorise operation at the numerical insulation-rating value.
Consider a hypothetical quotation where the project asks for operational-voltage evidence but the response supplies only an insulation-voltage entry. The correct outcome is an unanswered question, not an automatic rejection or acceptance of the component. Identify the missing operating-duty record and obtain clarification from the responsible source.
Do not turn this distinction into a field test. The meaning of a rating does not supply a safe test voltage, duration, instrument or procedure. Those decisions are outside this purchasing guide.
Why Uimp is not a continuous supply rating
OMRON's impulse-withstand glossary describes a prescribed impulse peak and its role as a reference for clearances. It is not a statement that the device can operate continuously at that peak value.
Keep the term impulse visible when transferring the record into an enquiry or comparison sheet. Otherwise a copied value can appear to be ordinary operating-voltage information. Preserve the original units and the manufacturer's stated conditions rather than converting or relabelling the entry to make two offers look alike.
A purchasing team can identify missing evidence; it should not calculate required clearances or select surge protection from this explanation. Refer unresolved design questions to the responsible engineer with the original documentation attached.
Check the symbol's document context
This article uses Ui in the switchgear insulation-rating context. Do not transfer that meaning to every document containing the same letters. The separate intrinsic-safety entity-parameter guide discusses Ui as an apparatus input limit within a different assessment.
When terminology is uncertain, retain the document title, section heading and complete label beside the value. Ask which definition applies. A shared abbreviation is not a technical cross-reference, and this article provides no intrinsically safe loop calculation or approval.
Make the comparison traceable to a real configuration
Start by identifying the ordered head, contact unit, indicator or other module rather than treating a front-view photograph as the complete electrical assembly. You can browse the listed panel-mounted control components to identify the product family discussed in an enquiry. The category does not establish any rating for a pictured item.
For each offer, record the full order reference, the particular circuit or function, the rating label as written and the source document revision. Put unresolved differences in a separate column. This is an editorial comparison method, not a prescribed compliance form.
If the quotation and datasheet use different suffixes, ask for a documented relationship before comparing their values. If the supplier changes a module, reopen the affected comparison rather than carrying the previous result forward. An alternative may be acceptable, but its identity needs to remain visible to the reviewer.
Keep the electrical and Ex evidence questions separate
The public IEC 60947-1:2020 record describes general low-voltage switchgear and controlgear rules when invoked by the relevant product standard. Its current catalogue copy includes the listed 2022 and 2024 corrigenda. The IEC 60947 series catalogue still lists that Part 1 edition on this review date.
IEC 60079-0:2026 separately addresses general construction, testing and marking of Ex Equipment and Ex Components. Neither a voltage label nor a standards catalogue entry verifies the conformity of an offered product. The circuit-breaker buyer guide discusses another example of keeping electrical performance and completed Ex evidence distinct.
Current MMAIATEX certification status
MMAIATEX is the public brand of MMAIATEX Explosion-proof Technology (Zhejiang) Co., Ltd. On the review date, its About page describes ATEX, IECEx and CCC certification as in progress. This attributed website statement is not independent certificate verification. Confirm the exact offered model, marking, current certificate scope and documentation before acceptance.
Safety and legal disclaimer
This guide explains purchasing terminology, not electrical design, insulation coordination, testing, installation or legal approval. It supplies no operating limits for a particular device. Competent project parties must assess the actual circuit, controlled product information and applicable requirements.
Contact MMAIATEX
Send the proposed component reference, the circuit or function concerned and the document entry needing clarification. Include the required operating duty and the source page containing the rating.