Capturing the requirement

Why the requirement comes first

Most problems with electrical equipment can be traced to a requirement that was incomplete or misunderstood: a load that was estimated rather than measured, a supply variation nobody recorded, an installation constraint discovered on delivery day. Invitrona treats the requirement as the first engineering output, before a product or rating is proposed.

What the requirement record holds

Each enquiry that proceeds to engineering review is recorded in a consistent form. The record separates information by its source and certainty:

• Stated need: what the customer has asked for, in their words
• Site or application facts: load lists, drawings, supply details and photographs provided
• Measured conditions: readings with their date, time and method
• Customer specification: any specification or standard the project requires
• Interpretation: how Invitrona reads the requirement where it is ambiguous
• Assumptions: values assumed in the absence of data, stated so they can be checked
• Open questions: information still needed, and who is expected to provide it

Keeping these apart matters. An assumption that looks like a fact is the most common source of a wrong selection.

How the record is built

The enquiry form collects the starting information. The engineering review then compares it with what the product class needs: the selection inputs listed on each product page and in the selection guides. Missing items are listed in the reply rather than filled silently. Where a site visit or measurement is needed, its purpose and scope are agreed first.

When the requirement is confirmed

A requirement is confirmed when the customer agrees that the record describes the duty correctly, or when a documented design basis is agreed instead. The proposal refers to that record by revision. If the requirement changes later, the record is revised and the effect on the proposal is reviewed; see controlling changes.

Measurements and site visits

Some requirements cannot be confirmed from documents alone. Voltage that varies through the day, an unbalanced three-phase supply, or a process whose load has never been logged all need measurement. When a measurement or site visit is proposed, its purpose, the readings to be taken, the duration and the safety arrangements are agreed first. Readings are recorded with their date, time, location and instrument, and estimates are marked separately from measured values. A short recording that misses the period of lowest voltage can mislead more than no recording at all, so the measurement period is chosen to cover the conditions that matter.

Questions you can ask

• Which items in the requirement record are measured, and which are estimated?
• Which assumption, if wrong, would change the proposal most?
• What information would remove the remaining open questions?

What this means for a buyer

You can see what the proposal is based on and what it assumes. If a fact in the record is wrong, it can be corrected before it becomes a design decision. And when the equipment is serviced years later, the conditions it was selected for are on record.