IEEE Std 2425-2025 - IEEE Standard for Electromagnetic Compatibility Testing of Electrical and Instrumentation and Control Equipment at Nuclear Power Generating Stations and Other Nuclear Facilities

Standard No.: IEEE Std 2425-2025
Release Date: 2026
Published By: Institute of Electrical and Electronics Engineers (IEEE) US / IEEE
Latest: IEEE Std 2425-2025

Introduction

Background of Standard Formulation and Technical Evolution

With the widespread application of digital instrumentation and control (I&C) systems in nuclear power plants, electromagnetic compatibility (EMC) issues have become increasingly prominent. Early nuclear power plants primarily relied on scattered standards such as IEC 62003, MIL-STD-461, and EPRI TR-102323, but lacked unified comprehensive requirements specifically tailored for the special environment of nuclear facilities. IEEE Std 2425™-2025 emerged accordingly, developed by the Nuclear Engineering Committee of the IEEE Power & Energy Society, approved on November 4, 2025, aiming to provide a complete set of EMC qualification methods for electrical and I&C equipment in nuclear power plants and other nuclear facilities.

This standard integrates military standards (MIL-STD-461), International Electrotechnical Commission standards (IEC 61000 series), and U.S. Nuclear Regulatory Commission (NRC) RG 1.180 guidelines, and based on NUREG/CR-6431 and EPRI measured data, determined test levels suitable for typical electromagnetic environments in nuclear power plants. In terms of technical evolution, the standard for the first time explicitly classifies equipment by installation location (control room, cable room, inside containment, etc.) and environmental severity, allowing test levels to be adjusted based on actual measurements or engineering assessments, reflecting a shift from "one-size-fits-all" to "risk-oriented" approaches. Additionally, the standard covers power quality tests (such as voltage dips, harmonics),弥补ing the previous limitation of focusing only on EMI/RFI.

Standard Framework Comparison: Path of Multi-Standard Integration

The most significant feature of IEEE 2425-2025 is the provision of two parallel testing method systems: military standards (MIL-STD-461) and commercial standards (IEC 61000 series). Users can choose one based on equipment type, application scenario, or regulatory requirements, but must meet equivalent limit requirements. The following table compares the differences in major test items:

Test Type	MIL-STD-461 Method	IEC Method	Applicable Port
Radiated Emission (Low Frequency)	RE101 (30 Hz-100 kHz, Magnetic Field)	No direct equivalent (Exemption or supplementary assessment possible)	Enclosure and Cables
Radiated Emission (High Frequency)	RE102 (2 MHz-10 GHz)	IEC 61000-6-4 (30 MHz-6 GHz)	Enclosure and Cables
Conducted Emission (Low Frequency)	CE101 (30 Hz-10 kHz)	None (Exemption possible based on THD)	Power Ports
Conducted Emission (High Frequency)	CE102 (10 kHz-10 MHz)	IEC 61000-6-4 (150 kHz-30 MHz)	Power Ports
Radiated Immunity (Magnetic Field)	RS101 (30 Hz-100 kHz)	IEC 61000-4-8/9/10 (50/60 Hz and Pulses)	Enclosure and Cables
Radiated Immunity (Electric Field)	RS103 (30 MHz-10 GHz, 10 V/m)	IEC 61000-4-3 (26 MHz-6 GHz, 10 V/m)	Enclosure and Cables
Conducted Immunity (Low Frequency)	CS101 (30 Hz-150 kHz)	IEC 61000-4-16 (DC-150 kHz, 10 V)	Power Ports
Conducted Immunity (High Frequency)	CS114 (10 kHz-30 MHz)	IEC 61000-4-6 (150 kHz-80 MHz, 10 V)	Power and Signal Ports
Surge (Combo Wave)	No direct equivalent (Reference C62.45)	IEC 61000-4-5 (4 kV Line-to-Ground, 2 kV Line-to-Line)	Power and Signal Ports
Electrical Fast Transient/Burst	No direct equivalent	IEC 61000-4-4 (4 kV Power Port)	Power and Signal Ports
Electrostatic Discharge	CS118 (8 kV Contact/15 kV Air)	IEC 61000-4-2 (Same as above)	Enclosure

Key Differences: The MIL-STD method covers lower frequencies (e.g., 30 Hz), making it particularly suitable for power frequency magnetic field interference present in nuclear power plants; while the IEC method is more detailed in the high-frequency range (>1 GHz) and signal line testing. The standard allows users to mix both methods, for example, using IEC 61000-4-5 for surge testing on power ports and MIL-STD-461 CS116 for damped oscillatory wave testing on signal lines.

Detailed Testing Technology and Application Cases

3.1 Radiated Emission Testing

The standard stipulates that radiated emissions must cover 30 Hz to 10 GHz. For the low-frequency range (30 Hz-100 kHz), the MIL-STD-461 RE101 method is used, measuring magnetic field with a loop antenna at a 7 cm distance, with limits of 160-90 dBpT (decreasing with frequency). For the high-frequency range, RE102 (2 MHz-10 GHz, limit 59-80 dBμV/m) or IEC 61000-6-4 (30 MHz-6 GHz, quasi-peak 40-47 dBμV/m @10 m) can be used.

Application Case: A nuclear power plant planned to install a new digital protection system in its control room, which contained high-speed switching power supplies within the enclosure. According to RE102 requirements, the radiated field strength measured in the 2-25 MHz band was 72 dBμV/m, exceeding the 59 dBμV/m limit. Engineers mitigated this by installing conductive gaskets on the enclosure and optimizing the grounding of the cable shielding layer (360° termination), reducing emissions to 57 dBμV/m and meeting the standard requirements.

3.2 Radiated Immunity Testing

The standard requires that equipment must not degrade in performance under an electric field strength of 10 V/m. MIL-STD-461 RS103 covers 30 MHz-10 GHz, while IEC 61000-4-3 covers 26 MHz-6 GHz (if the IEC method is used, the risk in the 6-10 GHz range must be assessed or RS103 supplemented). During testing, a linearly polarized antenna must be used to scan in both horizontal and vertical polarization directions, ensuring that the entire surface of the EUT and connected cables are irradiated.

Signal Generators and Power Amplifiers are key test equipment. For large cabinets (dimensions exceeding the antenna beam width), multi-position testing is required. The performance criterion is Class A: no functional degradation is allowed during or after the test.

3.3 Surge Withstand Capability (SWC)

Surge testing includes combo waves (1.2/50 μs voltage wave, 8/20 μs current wave) and ring waves (100 kHz). IEC 61000-4-5 specifies Level 1 power ports as 4 kV Line-to-Ground and 2 kV Line-to-Line; IEEE C62.45 recommends 6 kV. The standard allows reducing the level based on installation location: if the equipment is located on internal branch circuits (low exposure), it can be reduced to 2 kV; if located on external incoming lines (high exposure), the highest level must be applied.

Implementation Recommendations: It is recommended to install surge protection devices (SPD) at the equipment power entry and ensure that the SPD's voltage protection level (Up) is lower than the equipment's withstand voltage. For signal lines, shielded surge protection devices should be used, and attention should be paid to grounding loops.

3.4 Electrostatic Discharge (ESD)

ESD testing uses contact discharge at 8 kV and air discharge at 15 kV. MIL-STD-461 CS118 and IEC 61000-4-2 waveforms differ slightly (CS118 rise time 0.7-1 ns, IEC 61000-4-2 is 0.7-1 ns but with a slightly lower current peak). Test points include all metal parts accessible to operators, connector housings, indicator lights, etc. The performance criterion is Class A, with no resets or data errors allowed.

Application Case: During ESD testing of a safety-class DCS cabinet in a nuclear power plant, a momentary screen flicker occurred when air discharge at 15 kV was applied to the panel indicator lights. Analysis revealed that the indicator lights were not connected to the enclosure ground, causing static electricity to flow through internal logic circuits. The issue was resolved by connecting the metal frame of the indicator lights to the enclosure ground via a 1 MΩ resistor, after which the test passed.

3.5 Power Quality Testing

Appendix F of the standard states that if equipment is sensitive to power harmonics, IEC 61000-4-13 harmonic and interharmonic testing is required. Harmonic levels use Class 2 (general industrial), e.g., 3rd harmonic is 8% of fundamental voltage (18.4 V for a 230V system). Voltage dip testing requires equipment to maintain functionality without interruption during 40% residual voltage for 10/12 cycles. The standard also references IEC 61000-4-11/34 for classification requirements for equipment of different current levels.

Implementation Recommendations and Engineering Practice

1. Selection of Test Levels: Should be based on electromagnetic environment surveys of the actual installation location of the equipment. If general requirements are adopted (e.g., 10 V/m in control rooms), workload can be reduced; if the environment is special (e.g., near large motors), the level must be increased. It is recommended to refer to measured data in NUREG/CR-6431 or EPRI TR-102323.

2. Grounding and Shielding: Section 4.3 of the standard emphasizes that equipment grounding and cable shielding are critical. Cabinets should use conductive gaskets to achieve 360° shielding, and cable shielding layers should be terminated 360° at the entry point. It is recommended to follow the guidelines of IEEE Std 1050.

3. Documentation Management: Chapter 7 requires the development of detailed test plans (see Appendix D) and test reports (Appendix E). The test plan should include EUT description, test sequence, functional monitoring methods (Appendix C), performance criteria, etc. The test report must record anomalies and corrective actions for each test.

4. Exemption Principles: The standard allows exemptions for certain tests under specific conditions, e.g., low-frequency emissions can be exempted from CE101 if they do not affect power quality (THD<5%). However, technical justification documents must be provided.

5. Equipment Qualification Cycle: EMC qualification is part of equipment qualification and must be coordinated with IEEE Std 627 and IEC/IEEE 60780-323. It is recommended to conduct EMC pre-testing during the equipment design phase to avoid late-stage rectification costs.

Conclusion

IEEE Std 2425-2025 provides an authoritative and flexible technical framework for EMC qualification of nuclear power plants, capable of meeting regulatory requirements (such as NRC RG 1.180) while adapting to the specific environments of different nuclear facilities. By reasonably selecting testing methods and levels and strictly enforcing performance criteria, the reliable operation of nuclear-grade electrical and I&C equipment in complex electromagnetic environments can be effectively ensured. In the future, with the gradual application of wireless communication equipment in nuclear power plants (referencing IEC 62988), relevant EMC requirements are expected to be further refined in subsequent versions of the standard.

IEEE Std 2425-2025 Referenced Document

IEC 61000-4-2 Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement techniques – Electrostatic discharge immunity test
IEC 61000-4-3 Electromagnetic compatibility (EMC) - Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4 Electromagnetic compatibility (EMC) — Part 4-4: Testing and measurement techniques — Electrical fast transient/burst immunity test
IEC 61000-4-5 Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement techniques - Surge immunity test*， 2026-07-13 Update
IEC 61000-4-6 Electromagnetic compatibility (EMC) — Part 4-6: Testing and measurement techniques — Immunity to conducted disturbances, induced by radio-frequency fields
IEC 61000-4-8 Electromagnetic compatibility (EMC) — Part 4-8: Testing and measurement techniques — Power frequency magnetic field immunity test
IEC 61000-4-9 Electromagnetic compatibility (EMC) - Part 4-9: Testing and measurement techniques - Impulse magnetic field immunity test
IEC 61000-6-2 Electromagnetic compatibility (EMC) - Part 6-2: Generic standards - Immunity standard for industrial environments
IEC 61000-6-4 Electromagnetic compatibility (EMC) - Part 6-4: Generic standards - Emission standard for industrial environments
IEC 62040-2 Interpretation sheet 1 - Uninterruptible power systems (UPS) - Part 2: Electromagnetic compatibility (EMC) requirements
IEEE Std 1050 IEEE Guide for Instrumentation and Control Equipment Grounding in Generating Stations
IEEE Std 1100 IEEE Recommended Practice for Powering and Grounding Electronic Equipment
IEEE Std 1159 IEEE Recommended Practice for Monitoring Electric Power Quality
IEEE Std 141 IEEE Recommended Practice for Power Distribution in Industrial Plants
IEEE Std 2405 IEEE Standard for the Design of Chargers Used in Stationary Battery Applications
IEEE Std 519 IEEE Standard for Harmonic Control in Electric Power Systems
IEEE Std C62.41.1-2002 Guide on the surge environment in low-voltage (1000 V and less) ac power ciruits*， 2026-07-13 Update
IEEE Std C62.41.2 IEEE Recommended Practice on Characterization of Surges in Low-Voltage (1000 V and Less) AC Power Circuits Corrigendum 1: Deletion of Table A.2 and Associated Text
IEEE Std C62.45 IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC Power Circuits*， 2026-07-13 Update

IEEE Std 2425-2025 history

2026 IEEE Std 2425-2025 IEEE Standard for Electromagnetic Compatibility Testing of Electrical and Instrumentation and Control Equipment at Nuclear Power Generating Stations and Other Nuclear Facilities

IEEE Standard for Electromagnetic Compatibility Testing of Electrical and Instrumentation and Control Equipment at Nuclear Power Generating Stations and Other Nuclear Facilities

IEEE Std 2425-2025IEEE Standard for Electromagnetic Compatibility Testing of Electrical and Instrumentation and Control Equipment at Nuclear Power Generating Stations and Other Nuclear Facilities