IEC 61326-1

IEC 61326-1:2020 establishes electromagnetic compatibility (EMC) requirements for electrical equipment used in measurement, control, and laboratory applications. The standard addresses both electromagnetic emissions and immunity to ensure reliable operation in the intended electromagnetic environment without causing unacceptable interference to nearby equipment.

The standard applies to equipment powered by AC supplies below 1,000 V, DC supplies below 1,500 V, batteries, or directly by the electrical circuit being measured, such as certain self-powered measurement instruments.

IEC 61326-1 defines EMC requirements for three operating environments:

• Basic Electromagnetic Environment: Residential, commercial, and light-industrial locations.
• Industrial Electromagnetic Environment: Manufacturing facilities and industrial installations where higher levels of electromagnetic disturbances may occur.
• Controlled Electromagnetic Environment: Locations where electromagnetic disturbances are managed through installation practices, protective measures, or operational controls.

Immunity requirements depend on the intended electromagnetic environment, while emission requirements follow the applicable Class A or Class B classification under CISPR 11.

As a product-family standard, IEC 61326-1 generally takes precedence over generic EMC standards for equipment within its scope. Additional requirements may apply under the relevant IEC 61326-2 series.

IEC 61326-1:2020 covers a broad range of electrical and electronic equipment used for professional measurement, testing, process control, and laboratory operations.

Typical products and devices include:

• Measurement and Test Equipment: Digital multimeters, oscilloscopes, spectrum analyzers, signal generators, data acquisition systems, and electrical measurement instruments.
• Industrial Control Equipment: Programmable logic controllers (PLCs), process controllers, regulators, industrial automation controllers, and control modules.
• Laboratory Equipment: Analytical instruments, laboratory monitoring systems, sample preparation equipment, and in vitro diagnostic (IVD) laboratory devices.
• Sensors and Transducers: Pressure sensors, temperature sensors, flow measurement devices, signal converters, and industrial measurement transducers.
• Power Supplies and Associated Equipment: Dedicated power supply units, measurement power sources, and supporting equipment integrated into measurement or control systems.
• Data Monitoring and Recording Systems: Data loggers, digital recorders, monitoring instruments, and computerized measurement systems.
• Wireless-Enabled Measurement and Control Devices: Instruments incorporating Wi-Fi, Bluetooth, or other wireless communication technologies for monitoring, data transfer, or remote control.

Equipment incorporating radio functionality remains within the scope of IEC 61326-1 for applicable EMC requirements. However, additional radio regulatory requirements may apply depending on the technology and intended market.

For certain equipment categories, the applicable IEC 61326-2 particular standard may supplement or modify the general requirements of IEC 61326-1.

Regulatory requirements for placing products on the market vary by jurisdiction. While European regulations may recognize harmonized EN IEC standards as a means of demonstrating conformity, the United States and Canada impose separate electromagnetic emission and equipment authorization requirements. Manufacturers must identify the applicable regulations, national standards, and conformity assessment procedures for each target market.

For the European market, EN IEC 61326-1 is commonly used to support conformity assessment under the EMC Directive 2014/30/EU. When the applicable harmonized edition is cited in the Official Journal of the European Union, compliance with its covered requirements can provide a presumption of conformity with the corresponding essential requirements of the directive.

Manufacturers are responsible for preparing the technical documentation, conducting the appropriate conformity assessment, issuing an EU Declaration of Conformity, and applying the CE marking where required. The applicable European edition and harmonization status must be verified for the product.

IEC 61326-1 is also used as a technical reference in markets that adopt IEC standards directly or through national and regional equivalents. Manufacturers should verify the applicable national adoption, edition, regulatory requirements, and conformity assessment procedures for each target market.

Important: IEC 61326-1 is an EMC product-family standard, not a standalone market authorization or certification scheme. A compliant EMC test report can support regulatory conformity assessment, but market access depends on the applicable legislation, national requirements, and product classification.

IEC 61326-1:2020 establishes electromagnetic emission and immunity test requirements based on the equipment’s intended operating environment, electrical interfaces, and functional characteristics. The applicable test program is determined through an EMC test plan in accordance with Clause 5.

Electromagnetic Emission Tests

Radiated Emissions (CISPR 11): Measurement of electromagnetic disturbances radiated from the equipment enclosure and associated cables.

Conducted Emissions (CISPR 11): Evaluation of RF disturbances conducted onto power supply connections.

Harmonic Current Emissions (IEC 61000-3-2 / IEC 61000-3-12): Assessment of harmonic currents generated by equipment connected to public low-voltage power networks, where applicable.

Voltage Fluctuations and Flicker (IEC 61000-3-3 / IEC 61000-3-11): Evaluation of voltage changes and flicker caused by equipment operation, where applicable.

Electromagnetic Immunity Tests

Electrostatic Discharge (IEC 61000-4-2): Evaluates resistance to contact and air discharges.

Radiated RF Immunity (IEC 61000-4-3): Assesses equipment operation when exposed to radio-frequency electromagnetic fields.

Electrical Fast Transient/Burst (IEC 61000-4-4): Evaluates susceptibility to repetitive switching transients coupled onto power and signal cables.

Surge Immunity (IEC 61000-4-5): Assesses resistance to high-energy transient overvoltages on applicable electrical ports.

Conducted RF Immunity (IEC 61000-4-6): Evaluates susceptibility to RF disturbances coupled onto power and signal connections.

Power-Frequency Magnetic Field Immunity (IEC 61000-4-8): Evaluates the influence of 50 Hz or 60 Hz magnetic fields on magnetically sensitive equipment.

Voltage Dips and Short Interruptions (IEC 61000-4-11): Evaluates equipment behavior during temporary reductions or interruptions of AC supply voltage.

Note: Not every test is applicable to every product. Test selection depends on the electromagnetic environment, available ports, cable lengths, power supply characteristics, and applicable particular standards in the IEC 61326-2 series.

IEC 61326-1:2020 specifies immunity test levels according to the intended electromagnetic environment. The following tables summarize the principal requirements for basic, industrial, and controlled electromagnetic environments, as defined in Tables 1, 2, and 3 of the standard.

Radiated RF Immunity

Note: IEC 61326-1:2020 does not explicitly require radiated immunity testing between 1 GHz and 1.4 GHz. However, if this frequency range is tested, the standard recommends applying the same test level specified for frequencies above 1.4 GHz.

Other Principal Immunity Test Levels

Important: The immunity levels presented above apply to the specified equipment ports and electromagnetic environments. DC power ports and I/O signal/control ports have additional requirements and applicability conditions. Power-frequency magnetic field immunity applies only to magnetically sensitive equipment.

Voltage Dips and Short Interruptions

For equipment with applicable AC power ports, IEC 61326-1:2020 specifies voltage dip and interruption tests according to IEC 61000-4-11. The required residual voltage, test duration, and performance criterion depend on the electromagnetic environment.

Note: Residual voltage is expressed as a percentage of the rated supply voltage. Durations separated by a slash represent the number of cycles at 50 Hz and 60 Hz, respectively. The 0% residual-voltage tests lasting 250/300 cycles represent short interruptions.

For qualifying portable test and measurement equipment powered by batteries or the circuit being measured, Annex A specifies additional applicability provisions and immunity requirements.

Test Planning: The final EMC test matrix must consider the equipment’s power supply configuration, available interfaces, cable lengths, intended installation environment, and any applicable IEC 61326-2 particular requirements.

Compliance assessment under IEC 61326-1:2020 involves two distinct evaluations: electromagnetic emissions against applicable numerical limits and immunity performance against defined acceptance criteria.

Emission Limits and Equipment Classification

Clause 7.2 references CISPR 11 for emission limits, measurement methods, and equipment classification. Products must be assigned the appropriate Group 1 or Group 2 classification and Class A or Class B designation.

Class A: Equipment intended for non-residential environments and locations not directly connected to low-voltage networks supplying residential buildings.

Class B: Equipment suitable for residential environments and installations connected to public low-voltage networks supplying residential buildings.

Group 1: Equipment that does not intentionally generate and use RF energy for material treatment or inspection/analysis in the manner defined for CISPR 11 Group 2 equipment.

Group 2: Equipment intentionally generating and using RF energy for specified applications involving material treatment or inspection/analysis, as classified under CISPR 11.

The applicable conducted and radiated emission limits depend on the CISPR 11 classification, frequency range, measurement conditions, and test configuration. The exact numerical limits are obtained from the referenced edition of CISPR 11 rather than from separate emission-limit tables in IEC 61326-1.

Immunity Performance Criteria

Clause 6.4 defines three performance criteria used to assess equipment behavior during and after immunity testing:

Criterion A: The equipment must maintain its specified functional performance during and after testing, subject to the permissible performance deviations established for the equipment.

Criterion B: Temporary performance degradation may be permitted during testing, provided the equipment recovers automatically and no stored data is lost.

Criterion C: Temporary loss of function may be permitted, with recovery through automatic operation or operator intervention, provided the applicable conditions are satisfied.

Acceptable performance deviations must be established before testing and supported by the equipment’s functional specifications and documentation. Compliance is determined by the applicable test limits and performance criteria, not solely by whether the equipment remains powered on.

Clause 5 requires an EMC test plan to define the equipment under test (EUT), its representative configuration, operating conditions, and functional performance before testing begins.

Equipment Configuration: The test arrangement must represent a typical installation specified by the manufacturer. Relevant modules, power supplies, peripheral devices, auxiliary equipment, and external connections must be identified. Where multiple configurations exist, representative arrangements must be selected and justified.

Cabling and Grounding: Power, measurement, control, and communication cables must be installed according to the manufacturer’s specifications. Cable types, lengths, routing, shielding, and grounding arrangements should represent the intended installation. Additional grounding connections not specified by the manufacturer must not be introduced.

Operating Modes: Testing must include representative operating conditions, with emphasis on the estimated worst-case modes during normal use. Depending on the equipment, these may include maximum processing activity, active communication, measurement operation, switching activity, or simultaneous operation of relevant functions.

Functional Monitoring: Measurable performance parameters must be established before immunity testing. These may include measurement accuracy, output stability, communication integrity, control response, data acquisition continuity, and error indications. Applicable performance criteria must be documented in the test plan.

Software and Firmware: The software or firmware version used during testing must be recorded. Where necessary, dedicated test software may be used to exercise representative functions and monitor equipment performance.

The final test report must document the EUT configuration, operating modes, test arrangements, measured results, performance deviations, and any modifications made during testing.

Early EMC evaluation helps identify potential compliance issues before formal testing, reducing redesign costs and project delays. For measurement, control, and laboratory equipment, particular attention should be given to power supplies, sensitive measurement circuits, and external connections.

Recommended Engineering Practices

Power Supply Filtering: Minimize conducted emissions using appropriate common-mode and differential-mode filtering.

PCB Layout and Grounding: Reduce high-frequency current loops and separate sensitive analog circuits from switching and digital circuits.

Cable Shielding: Ensure proper shield termination, grounding, and cable routing to minimize electromagnetic coupling.

Interface Protection: Apply suitable ESD and surge protection to exposed power, measurement, and communication ports.

Pre-Compliance Testing

Conducted and radiated emission scans, near-field measurements, and targeted immunity tests can identify potential EMC failures during product development. Any corrective modifications should be verified before proceeding with formal compliance testing.

Note: Pre-compliance testing reduces compliance risk but does not replace formal testing against the applicable IEC 61326-1 requirements.