ISO 8528-5:2025

Overview

ISO 8528-5:2025 - "Reciprocating internal combustion engine driven alternating current generating sets - Part 5: Generating sets" defines the design and performance criteria for packaged generator sets (gensets) consisting of a reciprocating internal combustion (RIC) engine coupled to an AC generator. The sixth edition (2025) covers land and marine applications, for units that may operate in parallel with the public grid or stand-alone. It excludes aircraft applications and prime movers used to propel vehicles or locomotives. The document also serves as a basis for setting supplementary requirements for critical installations (e.g., hospitals, high‑rise buildings) and can inform requirements for other reciprocating prime movers (e.g., steam engines).

Key technical topics and requirements

ISO 8528-5:2025 focuses on the performance and interaction of the engine–generator unit. Major technical topics include:

• Frequency characteristics (no‑load, rated and safety frequencies; frequency setting and change rates)
• Voltage characteristics (rated, no‑load and adjustable voltage limits; voltage modulation and steady‑state tolerances)
• Sustained short‑circuit current and its implications for protection and generator sizing
• Factors affecting generating set performance: power, frequency/voltage behavior, load acceptance and transient response
• Cyclic irregularity, starting and stop‑time characteristics
• Parallel operation: sharing of active and reactive power between generating sets, and requirements when paralleling to the public grid
• Rating plates and nameplate information for correct identification and selection
• Additional influencing factors: fuel/lubrication, combustion air, exhaust, cooling and ventilation, monitoring, noise, coupling, vibration, foundations
• Performance class operating limit values and recommendations for specific prime movers such as gas engines

The standard also contains updated terms, symbols and illustrative figures to support consistent interpretation and testing.

Practical applications and who uses this standard

ISO 8528-5:2025 is intended for:

• Generator set manufacturers (design, testing, documentation)
• Marine and land OEMs integrating gensets into systems
• Power system and controls engineers (paralleling, protection, governor/AVR settings)
• Specifiers, procurement teams and facilities managers for hospitals, data centers, buildings and industrial sites
• Testing laboratories and conformity assessors
• Consultants and regulatory authorities drafting supplementary or safety requirements

Using ISO 8528-5 helps ensure reliable dynamic behavior, safe parallel operation, correct rating information and consistent performance across installations.

Related standards

Part of the ISO 8528 series. Key normative references include:

• ISO 8528-1:2018 (Application, ratings and performance)
• ISO 8528-3:2020 (Alternating current generators)
• ISO 3046-5 (Torsional vibrations)
• IEC 60034‑1 (Rotating electrical machines - Rating and performance)

For the full technical requirements and test procedures, obtain the complete standard from ISO or your national standards body.