EMC, EMI and EMS

What is Electromagnetic Compatibility (EMC)?

When a device reprocesses, propagates or receives electromagnetic energy, this can have very negative consequences. This electromagnetic energy can cause a device to suffer from Electromagnetic Interference (EMI), also known as Radio Frequency Interference (RFI). It is also possible that these interference signals cause physical damage to a device. In order to prevent these problems, EMC guidelines have been drawn up stating that all electrical equipment must comply with certain emission and immunity limits. These limits are intended to ensure that a device always operates correctly in an environment where other electrical devices or EMI sources are used.

What is EMI/RFI?

All electrical or electronic components and devices generate electromagnetic fields. These interference signals can interfere, for example through induction, with components or circuits within a device which can cause a device to malfunction or fail to function at all. These electrical interference fields are called Electromagnetic Interference (EMI). As described earlier, this is also referred to as Radio Frequency Interference (RFI).

What is EMS?

EMS, or Electromagnetic susceptibility, is the extent to which electronic equipment is insensitive to disturbing fields or external voltages. EMS is also referred to as the immunity of electrical equipment.

EMC testing

All electrical and electronic products that are made, designed or imported must comply with the EMC guidelines. These guidelines offer the users of the devices all over the world better reliability and safety. In addition to the safety and reliability of the equipment, the EMC guidelines have also been drawn up to prevent interference from equipment with nearby television/radio receivers. The so-called EMC compliance tests are carried out to determine whether a device complies with these guidelines. The compliance tests consist of two parts, which will be described below.

Emission testing

As described above, an electrical or electronic device can generate interference signals. This EM-emission can be emitted by the device but can also be conducted by a power line. During an emission test, the exact EM emission of the device to be tested is examined and whether it does not exceed the set limits.

Immunity testing

In immunity tests, EM energy is deliberately sent to a device to see how the device reacts to this energy. With this test it is possible to see how immune the device to be tested is to EM-energy.


How is an EMC (pre-)compliance test performed and what equipment do I need for it?

In order to get a product certified for EMC, it is necessary to have tests carried out in an accredited compliance laboratory. In the Netherlands there are several labs, such as DARE , Bicon or the lab of Philips at the HTC. Such a test is not only very expensive, it is also quite an operation because the test setup has to be transported with the Device Under Test (DUT) and has to be rebuilt. In order to gain insight in advance whether there is a good chance of success of such a full-compliant test, you can carry out a pre-compliant test yourself, in your own lab. This way EMC problems in a design can be detected early and a lot of money can be saved. But how do you do such a test? And what equipment do you need for it? Below you will find a brief explanation of which devices Eleshop sells and how they can be used to perform pre-compliance tests.

Spectrum analyser (with Quasi-peak detection)

In EMC pre-compliance testing, it is important that the spectrum analyser is equipped with Quasi-peak detection. Normal peak detection keeps the peak value of a signal, this indicates the worst case scenario. Quasi-peak detection weighs each component on the basis of how frequently it occurs. This means that when a peak occurs more often, this component gets a higher weight in the measurement. When making measurements from your Device Under Test, you can compare the measured quasi-peak values with the quasi-peak limits in the EMC guidelines. This way you can see for yourself whether the device will (probably) comply with the guidelines or whether the design will have to be changed. Eleshop sells various spectrum analysers of the brands Rigol, Owon, Siglent and Rohde & Schwarz.

SSA3000X series

Siglent's SSA3021X and SSA3032X are currently the most popular spectrum analysers due to their exceptional price/quality ratio. These analysers have a bandwidth of 2.1 and 3.2 GHz respectively and are standard delivered with Tracking Generator. The pre-compliance software including Quasi-peak detector and EMI filters can be ordered separately on our site.

Siglent SSA3021X spectrum analyser
1299 €1,299.00 Excl. VAT
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RSA3000 Series

If you have a larger budget you can also look at some more expensive spectrum analysers with better specifications, such as lower noise and higher bandwidth. The RSA3000 series from Rigol is a series of spectrum analysers that, especially for pre-compliance tests, is very well known. In addition to the 'normal' sweep mode, this series also has a real-time measurement mode. With this real-time mode, short and fast signals can be better captured, which can be very important in pre-compliance testing. Also, this series, compared to the earlier mentioned SSA3000X series from Siglent, has a lower phase noise, greater amplitude range and lower DANL (Displayed Average Noise Level). The complete pre-compliance software including for example Quasi-peak detector and EMI filters can be found for this series on this page. More information on how to use these applications step by step you can find here

Rigol RSA3015E-TG spectrum analyser
1768.6 €1,768.60 Excl. VAT
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RF probes

RF probes are used to easily measure if and where there is Electromagnetic Emission. The probes are connected to the spectrum analyser after which the magnetic fields and disturbance currents in the DUT can be measured. Eleshop sells separate RF probes and sets from the brands Tekbox, Beehive, Siglent and GW Instek.

Tekbox near field probe set

The EMC near field probe set from Tekbox is a very affordable and good set of probes for EMC measurements. The probe set has 3 magnetic field and 1 electric field probe and can be used up to 6 GHz! This set also comes standard with SMB to SMA cable and an SMA-female to N-male adapter.

Tekbox TBPS01 EMC near field probe set
206.61 €206.61 Excl. VAT
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GKT-008 EMI probe kit

The GKT-008 EMI probe kit from GW Instek is the best set of EMI probes on our site. This set consists of 4 probes which, due to their design, are much less dependent on position and orientation when making measurements. Conventional probes (such as the probes of Tekbox or Beehive) give different measurement results if they are oriented in different ways in relation to the measurement object. The probes in this set are not affected by this. Attention! The included software only works with a GSP-9300 spectrum analyser. The probes can be used with another spectrum analyser.

GW Instek GKT-008 EMI probe kit
805.5 €805.50 Excl. VAT
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LISN (Line impedancestablishment network)

A LISN is a low-pass filter that is placed between the AC or DC power supply and the DUT. The LISN is a device that is used in combination with a measuring receiver or spectrum analyser to measure the interference on a supply line. As the name suggests, a LISN creates a stabilized fixed measurement impedance regardless of the impedance of the power source. The RF interference is coupled with minimal losses to a 50Ω BNC terminal where the interference can be analyzed for example with a spectrum analyser. In this way, a conducted noise measurement of a power line can be done. Eleshop sells LISNs of the brand Tekbox. Pay attention if you want to test a device that is powered by a DC or AC power supply!

DC LISN

The Tekbox TBOH01 is a DC LISN that can be used to measure the conducted noise on the power line of DC-powered devices. Specifications of this LISN can be found on the product page below.

Tekbox TBOH01 - DC LISN 60V 10A
274 €274.00 Excl. VAT
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AC LISN

The Tekbox TBLC08 is an AC LISN that can be used to measure the conducted noise on the power line of AC-powered devices. Specifications of this LISN can be found on the product page below.

Tekbox TBLC08 - AC LISN 240V 8A
764.46 €764.46 Excl. VAT
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LISN MATE

Optionally you can also choose to purchase a 'LISN Mate'. The Tekbox LISN Mate is a device that can be used in conjunction with a Line Impedance Stabilisation Network. The noise signal that can be analyzed with a LISN consists of the sum of a 'common mode' and a 'differential mode' component. With this LISN degree, these two components can be split up and analyzed on a separate BNC port.

Tekbox TBLM01 LISN Mate
268.6 €268.60 Excl. VAT
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Power limiter (Optional)

Power Limiter

A power limiter is used to protect your spectrum analyser against excessive input power. Eleshop sells a power limiter from RF Explorer for a fraction of the price of repairing a blown up input (apart from the down-time). In addition to the standard protection for measurements of fields up to 30 dBm and 3 GHz, this limiter also has a direct current protection up to 16 V.

RF Explorer power limiter / DC block
49.54 €49.54 Excl. VAT
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General EMC standards and their meaning

The pre-compliance measurements that we have discussed in this article can be used for the following standards:
Standard Description Specific band/limit
EN61000-6-2 Immunity (industrial environments)
EN61000-6-3 Emission (residential, commercial and light-industrial environments)
EN61000-6-4 Emission (industrial environments)
CISPR 11 Electromagnetic disturbance characteristics (Industrial, Scientific and Medical (ISM) radio-frequency equipment) RE 30 MHz - 1000 Mhz
CE 9 kHz - 30 MHz
CISPR 14 Requirements for household appliances, electric tools and similar apparatus RE 30 MHz - 1000 MHz
CE 150 kHz - 30 MHz
CE 30 MHz - 300 MHz
CISPR 16 Specification for radio disturbance and immunity measuring equipment and methods RE 30 MHz - 1000 MHz
CE 9 kHz - 30 MHz
CISPR 22 Radio disturbance characteristics (Information Technology Equipment (ITE)) RE 30 MHz - 1000 MHz
CE 150 kHz - 30 MHz
EN61000-3-2/3 Part 3: Limits
Section 2&3: Limits for harmonic currents emissions and Limitation of voltage fluctuations and flicker in low-voltage supply systems for equipment with rated current up to 16A
<16 A
EN61000-4-x Part 4: Immunity tests <30 kV