Keeping Film-Capacitor AC, DC and Category Voltage Ratings Separate

1. Identify what the voltage field measures

A film-capacitor list with a column headed voltage can conceal several different meanings. Before comparing entries, identify the term used in the applicable product record. Vishay's introduction defines rated DC voltage, rated AC voltage and category voltage separately. The number is only one part of that description; losing the field's basis can make unlike ratings look as if they answer the same question.

The rated DC definition concerns a continuously applied DC voltage within its stated temperature context. The rated AC definition concerns a maximum RMS voltage at a specified frequency, also within its stated temperature context. Preserve those distinctions qualitatively. This guide does not provide a numerical rating, derive a peak value or turn one manufacturer's introductory definition into a limit for an unidentified capacitor.

Copy the original field name, units and applicable document reference together. Where a label or an old spreadsheet omits AC, DC or the rating name, retain the original reading and mark the basis unresolved. Do not select a field simply because another capacitor in the same equipment used that notation. The aim is a correctly identified rating description before a recipient assesses the released material.

2. Preserve rating conditions qualitatively

Temperature is part of the distinction in Vishay's definitions. Its rated-voltage descriptions refer to operation below the rated temperature, while category voltage is defined at the upper category temperature. Category voltage can concern AC or DC. It should therefore retain that context instead of being treated as another interchangeable name for whichever rated-voltage entry appears elsewhere in an inventory record.

Keep the applicable frequency context with a rated AC RMS entry. A shortened record that preserves RMS but drops the stated frequency has removed part of the definition. Do not replace it with a familiar supply frequency or assume one condition covers every product. If the exact document's conditions have not been identified, state the missing reference rather than supplying an apparently complete AC description.

Separate a rating condition from an actual operating-history statement. The temperature basis attached to a specification does not show where surplus material was stored or operated. Equally, a prior equipment log does not redefine the manufacturer's field. Keeping those records apart allows a reviewer to see whether the open question is the meaning of the rating or the history of the actual units.

3. Keep rating basis outside application conversion

Do not calculate an AC rating from a DC entry or a DC rating from an AC entry to complete the offer. The documented fields have their own definitions and conditions. A warehouse label does not provide the further product and application evidence needed to approve another operating limit. The classification can remain useful without claiming an equivalence between the different rating descriptions.

This is also separate from an X or Y class entry. That field addresses another manufacturer classification and its supporting documentation. Nor is a film-capacitor voltage rating the AC-input or DC-input identity of a power-supply module. Keeping the product and the quantity being described explicit prevents a general word such as AC from erasing the technical distinction between those different inventory questions.

If a recipient needs to assess a particular circuit, preserve that as a further review request. Provide the exact capacitor identity and the rating reference without presenting the inventory exercise as engineering approval. No mains eligibility, certification, connection instruction or suitability conclusion follows from this guide. It records the supported rating basis and leaves application decisions with the relevant technical evidence.

4. Offer voltage-basis-identified groups

Arrange the product description so rated DC, rated AC RMS and category-voltage entries remain recognisable where available. A missing field should stay missing; it does not acquire a value from another column. Where records disagree, retain their sources and identify which rating term needs reconciliation. This preserves the actual technical question instead of hiding it in a generic voltage mismatch.

For an ICULTRA film-capacitor enquiry, share the full available code, original rating wording and its conditions, stating any unidentified basis. Use the stock-list guide for quantities and release records. This preparation distinguishes documentation-supported groups without changing the capacitor, promising a verified operating limit or committing a buyer to accept the material. Any further assessment and purchase terms require confirmation for the specified lines.

Sources and further reading

• Vishay: Film Capacitors Introduction, construction and General Definitions

Vishay’s film-capacitor General Definitions support the rating distinctions. No numerical limit, RMS/peak conversion, mains classification or approval of an application is supplied.