WG 11 - TC 45/SC 45A/WG 11

IEC 63046:2020 provides requirements and recommendations for the overall Electrical Power System. In particular, it covers interruptible and uninterruptible Electrical Power Systems including the systems supplying the I&C systems; This document is consistent and coherent with IEC 61513. Like IEC 61513, this document also highlights the need for complete and precise requirements, derived from the plant safety goals. Those requirements are prerequisites for generating the comprehensive requirements for the overall Electrical Power System architecture, and for the electrical power supply sub-systems. This document establishes the high level specification and requirement to implement a suitable Electrical Power System in a NPP that supports reactor systems important to safety. It also enables electrical energy production providing the transmission grid with active and reactive power and electro-mechanical inertia.

IEC 61225:2019 specifies the performance and the functional characteristics of the low voltage static uninterruptible power supply (SUPS) systems in a nuclear power plant and, for applicable parts, in general for nuclear facilities. An uninterruptible power supply is an electrical equipment which draws electrical energy from a source, stores it and maintains supply in a specified form by means inside the equipment to output terminals. A static uninterruptible power supply (SUPS) has no rotating parts to perform its functions.
This third edition cancels and replaces the second edition published in 2005. This edition includes the following significant technical changes with respect to the previous edition:
a) the principal objective of this edition is to address the requirements on the static uninterruptible power supplies in nuclear power plants;
b) in addition to Instrumentation and Control (I&C) power supplies include all static uninterruptible power supplies;
c) emphasize that the static uninterruptible power supplies shall protect the connected equipment (loads) from transients on the on-site AC distribution system (the immunity concept);
d) in accordance with the defence-in-depth concept, this standard applies to static uninterruptible power supplies for all equipment, not only for equipment important to safety, with a graded approach to verification and validation;
e) addition of the requirement that, when batteries are connected in parallel under abnormal operating conditions, they shall be properly protected with isolation devices to avoid any failure that may impair more than one division of the uninterruptible power supply.

IEC 62855:2016 provides the electrotechnical engineering guidelines for analysis of AC and DC electrical power systems in nuclear power plants (NPPs) in order to demonstrate that the power sources and the distribution systems have the capability for safe operation and shut down of the NPP, bringing it to a controlled state after an anticipated operational occurrence or accident conditions and finally reaching a safe state. This standard is intended to be used:
- for verification of the design of new nuclear power plants;
- for demonstrating the adequacy and impact of major modifications of electrical power systems in operating nuclear power plants;
- and where there is a requirement to assess and establish operating limits and constraints for existing plants.