IEEE PC62.21/Cor1/D4, Oct 2007 is an inactive corrigendum document for a power and energy engineering standard, issued to replace Table 2 and Annex A.1 and A.2 in IEEE C62.21-2003. It matters because even a targeted correction can affect how equipment ratings, test data, and reference values are interpreted in insulation coordination and related electrical power applications. For organizations working with the standard, this document helps preserve consistency and technical accuracy in specifications and compliance reviews.

IEEE PC62.21/Cor1/D4, Oct 2007 overview

This corrigendum is part of the IEEE C62.21 family and serves a narrow but important technical role: it revises specific tabular and annex material rather than introducing a full new standard. In practice, that means users should consult it when applying the base document to ensure the corrected information is used alongside the 2003 edition. IEEE PC62.21/Cor1/D4, Oct 2007 is therefore most relevant where precise reference values and annex guidance affect engineering decisions.

Typical use cases

This document is typically used when reviewing or implementing the corrected table and annex content in power-system design, equipment specification, and test planning. It is especially relevant for engineers comparing insulation-related values, evaluating conforming equipment, or checking documentation against the amended IEEE C62.21 framework. In procurement and quality workflows, IEEE PC62.21/Cor1/D4, Oct 2007 may be consulted to confirm that the latest corrigendum information is reflected in calculations, acceptance criteria, or technical submittals.

Why this standard matters

Correcting a table or annex can change how a requirement is read and applied, which is why this standard matters in practice. It supports more reliable compliance checks, reduces the risk of using outdated reference data, and helps maintain consistency across design, testing, and documentation. For power, energy, and industry applications, IEEE PC62.21/Cor1/D4, Oct 2007 provides a controlled reference point that can improve technical confidence and limit avoidable interpretation errors.

• Corrigendum to IEEE C62.21-2003
• Replaces Table 2
• Updates Annex A.1 and A.2
• Relevant to insulation and rating references
• Inactive IEEE standard document