IMMUNITY

Immunity is the ability of a device or system to resist the effects of electromagnetic disturbances or interference (EMI) and continue to operate correctly.

Immunity is the opposite of Emissions and so it is important to expect that a device or system is able to operate correctly in the presence of the same levels of noise that a standard deems allowable for it itself to produce.

Immunity testing involves exposing the product to a range of electromagnetic disturbances and measuring its ability to continue functioning correctly.

The most common types of immunity tests include: Conducted RF Immunity, Radiated RF Immunity, Electrostatic Discharge (ESD), Electrical Fast Transients (EFT), Magnetic Field Immunity, Voltage Dips & Interrupts and Surges.

To ensure that electronic equipment is immune to electromagnetic disturbances, designers can use techniques such as filtering grounding and shielding.

We stock a range of different products to help you find a fix for any Immunity issues.

CONDUCTED IMMUNITY

Conducted immunity refers to a device or system's ability to resist unwanted RF voltages and currents that get coupled to the external wires and cables or continue to operate correctly.

Conducted immunity testing involves simulating potential disturbances from other devices powered by the same power network or inductively coupled onto its external signal wires or cables.

Conducted immunity is an essential aspect of EMC, and it ensures that electronic equipment can function correctly in the presence of electromagnetic disturbances. EMC regulations define limits for conducted immunity to ensure that electronic devices and systems do not cause harmful interference to other devices and can coexist in the electromagnetic environment.
IEC 61000-4-6 by the International Electrotechnical Commission is the standard for induced disturbances caused by electromagnetic fields coming from intentional radio frequency (RF) transmitters in the frequency range of 150 kHz to 80 MHz.

See what we stock to help fix Conducted Immunity issues here.

emcfixSHOP Power Line Filter

Example: Noise on your power lines is finding its way into your product and causing it to operate unexpectedly - just like for Conducted Emission, our range of power line filters is a great place to start!

When selected correctly, the right filter will help to stop unwanted noise getting in to your product.

Filters

RADIATED IMMUNITY

Radiated Immunity ensures that electronic devices and systems can continue to operate correctly and safely in the presence of emissions form other devices and systems.

Radiated Immunity testing involves exposing the product to a range of electromagnetic disturbances through the air and measuring its ability to continue to operate correctly.

Radiated Immunity tests are quite similar to Radiated Emissions tests - the main difference is that power is injected through an antenna instead of being measured - so many of the steps taken to improve a product's emissions can also be used to improve it's resilience.

Click here to explore our range of products designed to help you with Radiated Immunity problems.

emcfixSHOP EMC Gasket

Example: Your product is going into a harsh environment and is struggling to continue to operate correctly in the presence of high levels of electromagnetic noise from other nearby devices - adding EMC gasket to your enclosure can help improve the robustness of your product in the presence of EMI by sealing gaps and filtering out unwanted noise.

Click here to see an example of one of our EMC gasket materials.

Other EMC Essentials

ESD

Electrostatic Discharge (ESD) is a sudden and
momentary flow of electric current between two differently charged objects when
brought close together or when the charge is discharged through and electronic device
or system.

ESD can cause interference to the operation of a device or system and in extreme cases can cause catastrophic failures.

We stock a number of different products to help recue the effects of ESD on your product.

emcfixSHOP Varistors

Example: High voltage ESD pulses are causing your device to behave erratically - Varistors may help to reduce the effect of ESD strikes by limiting the voltage that is able to make it through the rest of the circuit. There are very useful on any customer-facing signal lines!

Varistors

ELECTRICAL FAST TRANSIENTS (EFT)

Fast transients, also known as Electrical Fast Transients (EFT), are a type
of electromagnetic interference (EMI) that can cause malfunctions, degrade
performance, or even lead to catastrophic failure in electronic devices.

Fast transients are caused by voltage spikes or bursts that are generated by switching events or inductive load changes.

Fast transient testing measures a device's capability to withstand the transient phenomenon of these electrical burst.

EMC regulations define limits for fast transient immunity to ensure that electronic devices and systems do not cause harmful interference to other devices and can coexist in the same electromagnetic environment.

See our products that can help fix EFT issues here.

EFT Products
emcfixSHOP Varistors

Example: Transients are making it through the power lines and into your product - Varistors on the power lines may help to reduce the effect of the transients by limiting the voltage that is able to make it through the rest of the product.

Varistors

MAGNETIC FIELD IMMUNITY

Mains-frequency magnetic field is a type of electromagnetic interference (EMI) that can cause malfunctions, degrade performance, or even lead to catastrophic failure in electronic devices.

During a Magnetic Field test, a device is subjected to a magnetic field generated by a power generator and the performance of the device or system is monitored.

See our range of products for help fix Magnetic Field Immunity issues here.

Conductive Foam (1m width, 1m length, 0.5mm height)-Würth-emcfix shop

Example: Magnetic fields are causing some sensitive parts of your product to fail - preventing unwanted noise getting to sensitive circuitry can be done with ferrite sheets and noise absorbers! See an example of what we stock here.

Other EMC Essentials

VOLTAGE DIPS & INTERRUPTS

Voltage dips and interrupts are events that occur due to faults in a power network by sudden changes of large loads.

These events can affect electrical and electronic equipment, so they need to be simulated and tested to asses a device or systems ability to withstand their potential effects.

Voltage dips, short interruptions, and voltage variations are immunity tests defined by standards for specific territories or region, e.g. IEC 61000-4-11.

Here are our products to help with Voltage Dips & Interrupts.

emcfixSHOP Power Line Filter

Example: During a momentary power interruption, your product is operating incorrectly - this may be due to voltage dropping below critical operating thresholds and so you may need to some hold-up capacitance to your critical lines. Our range of power filters may have just the right combination of filter components to help you withstand any momentary losses in power.

Filters

SURGES

Mains surge is a type of electromagnetic interference (EMI) that can cause malfunctions, degrade performance, or even lead to catastrophic failure in electronic devices and systems.

Mains surge are commonly caused by voltage spikes or bursts that are generated by switching events or inductive load changes.

Click here to explore our range of products designed to help you with Surge immunity.

Varistor (48V DC, 5.4W)-Würth-emcfix shop

Example - A surge event has caused a catastrophic failure of your product - adding varistors to power lines can help to reduce the effect of any surges on the lines.

Varistors

SUMMARY

EMC Immunity is essential to ensure that electronic devices and systems do
not cause harmful interference to other devices and can coexist in the same electromagnetic
environment.

To ensure that electrical equipment functions reliably in a hostile electromagnetic environment, product designers and manufacturers must ensure that their products operate within the acceptable limits of interference immunity defined by specific standards and include suppression measures to protect against unexpected behaviour and damage.

STILL UNSURE?

We have tried our best to provide as much information as we can to help you find the right fix for your EMC issues - if you need further help, contact us using the button below or try our interactive Product Selector tool.

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