GeneralEMC Testing and Its Importance in the Medical Industry

EMC/EMI testing concerns almost every industry that involves the design, manufacture, or testing of electronic products. EMC (Electromagnetic Compatibility) testing is performed to ensure that electrical or electronic devices do not emit large amounts of electromagnetic interference. This is a similar part of the manufacturing process to FDA Quality System Remediation, so that no products are made with errors. It also confirms if your device or equipment can function in the midst of various electromagnetic phenomena.

Why is EMC Testing Important?

EMC testing is extremely important because it ensures that the electromagnetic spectrum and all the frequency bands that the devices use stay uncompromised.

In many industries such as health, automotive and aerospace, this testing is needed to safeguard electrical and electronic systems. It also ensures high device performance and quality by assessing the external and internal EMC phenomena affecting the device.

Moreover, failure to comply with EMC regulations can result in hefty fines, which is all the more reason why EMI testing cannot be avoided.

Electromagnetic compatibility testing can be categorized into the following:

• Immunity Testing
• Immunity testing measures how a device will react when subjected to disturbances and interferences such as electromagnetic noise.
• Through immunity testing, the reliability of the electrical and electronic devices can be assessed within certain operating conditions and limits. It ensures the smooth functioning of devices in a given environment.

 

• Emissions Testing
• Emissions testing gives information about the amount of electromagnetic noise that an electronic device or equipment generates while being operated.
• This test checks if all the emissions from the device are below the relevant limits defined for that type of device. This ensures that the device itself does not produce any harmful interference or emissions during its operation in a given operating environment.

EMC testing equipment is used to perform the above tests and analyze the electromagnetic emissions and compatibility of a device. A typical EMC testing system may utilize equipment such as surge generators, power amplifiers, spectrum analyzers and more.

EMC Testing in the Medical Industry

EMC testing is essential for risk management in the medical industry, especially in the manufacturing of medical devices and equipment. Different devices must be able to work together in close environments without electromagnetic interference causing the malfunction of medical equipment. Reducing electromagnetic emissions and the issues that arise from electromagnetic compatibility is critical because even a little disturbance in medical devices can be highly destructive.

With medical wearables gaining popularity, the need for EMC testing is higher than ever before, since the risk of electromagnetic interference is not limited to within the hospitals or medical facilities anymore. A person wearing medical devices could be anywhere and would be subject to various kinds of electromagnetic radiations from common devices such as microwaves and mobile phones, and transportation vehicles like trains and airplanes.

Medical equipment and devices such as defibrillators, ultrasound systems, ventilators, and MRI (Magnetic Resonance Imaging) systems need to be extremely reliable and efficient, and should be able to withstand external electromagnetic interference without compromising on performance. EMC compliance testing is required in such cases in order to design, analyze and troubleshoot the equipment for enhanced device immunity. Once the devices undergo testing, they can be improved with the help of EMI mitigation techniques.

Current EMI/EMC Standards and Requirements for Medical Equipment

To ensure extended immunity, enhanced performance and high safety, the FDA requires all medical devices and equipment to undergo EMI/EMC testing as per the appropriate FDA Reviewer Guidance document or the International Electrotechnical Commission (IEC) 60601-1-2 standards, “Medical Electrical Equipment—Part 1: General Requirements for Safety, Amendment No. 2. Collateral Standard: Electromagnetic Compatibility Requirements and Tests.”

In the EU, all medical devices are required to have a CE marking, which should have both immunity and emissions testing as per the IEC 60601-1-2 standards.

The IEC 60601-1-2 standards lay down guidelines for medical device testing and provide specifications such as the test limits for emissions, immunity, electrostatic discharge (ESD), radiated radio-frequency electromagnetic fields, bursts, and surges.

Emissions

• Equipment should comply with the emissions requirements as specified by the International Special Committee on Radio Interference (CISPR).
• The requirements and amplitude levels are specified in the CISPR 11, which covers a frequency range from 150 kHz to 18 GHz.

Immunity

• Immunity test levels and test methods are based on the IEC 801 series of immunity requirements.
• Compliance testing should be performed for detecting any safety hazard and all guidelines for avoiding or identifying and resolving adverse electromagnetic effects should be included in the documentation.

ESD – Electrostatic Discharge

• Equipment should comply with the IEC 801-2 requirements.
• For direct contact discharge to all conductive accessible parts and coupling planes, the limit is 3 kV. The limit is 8 kV for air discharge to non-conductive accessible parts.

Radiated Radio-frequency Electromagnetic Fields

• Equipment should comply with the IEC 801-3 standards and requirements.
• A limit of 3 V/m should be used over a frequency range of 26 MHz to 1 GHz.
• Other levels apply to equipment used in shielded locations, such as X-ray and MRI systems.
• The 3-V/m requirement is decreased with the increasing shielding effectiveness of the location.

Bursts

• Equipment should comply with the test methods and instruments specified in IEC 801-4.
• A 1-kV level applies to equipment connected to the power line with a plug. For permanently installed equipment, a level of 2 kV applies. Interconnecting lines longer than 3m should be able to withstand a surge of 0.5-kV.

Surges

• Equipment should comply with the test methods and instruments specified in IEC 801-5.
• Power lines should meet levels of 1 kV for differential mode and 2 kV for common mode. Signal lines are not required to be tested, and telecom lines are covered by other standards.

Summary

With constant innovation and development of medical electrical equipment and systems, the electromagnetic spectrum gets more and more congested. Medical devices are being used in environments outside of hospitals, and hence, different EMI/EMC standards need to be met, to test all environments of intended use.

Rigorous EMC testing and troubleshooting would ensure greater safety of people and protection of medical equipment. Superior quality EMC testing equipment should be used to perform efficient testing and analysis and to achieve reliable results.