What Standard to Use?

Since Jan. 1, 1996, all electric and electronic products exported to European countries must meet the European EMC requirements. If there is no specific standard for the product, the generic immunity standard applies.

There are two parts of the generic immunity standard: EN 50082-1 and EN 50082-2. EN 50082-1 is used for residential, commercial, and light industry; EN 50082-2 is used for industrial environments.

Currently, there are two versions of EN 50082-1: 1992 and 1997. As the expiration date of July 2001, approaches, need for a comparison of the two versions is necessary.

Immunity Test

We will first focus on the immunity requirement, EN 50082-1: 1992, and the standards called out for immunity testing: IEC 801-2, IEC 801-3, and IEC 801-4. These test requirements were just the beginning of better things to come.

Then the EU proposed a generic standard, prEN 50082-1: 1994, to replace EN 50082-1: 1992. The reason for the proposed change could have been expected. When technologies become more advanced and more electrical/electronic devices are manufactured, the testing must reflect the current disturbances found in an electromagnetic environment.

The 1992 version of the immunity requirements contained tests that no longer were realistic. The new version, EN50082-1: 1997, included tests for commonly found environmental disturbances. With the additional requirements found in the 1997 immunity version, the equipment under test (EUT) must pass tests involving these disturbances that exist in the everyday world.

The 1992 version of EN 50082-1 is based on the IEC 801 Series, Electromagnetic Compatibility for Industrial-Process Measurement and Control Equipment. The 1997 version is based on EN 61000-4 Series, Electromagnetic Compatibility, Part 4. Testing and Measurement Techniques.

The test requirements for these two versions are shown in Table 1 and Table 2. The 1992 version requires passing three separate immunity tests, and the 1997 version requires passing seven separate immunity tests to satisfy the requirement. The comparison between these two versions will be discussed in detail under each test item.

ESD

Both versions require a test for electrostatic discharge (ESD), but the test setup is different. For tabletop EUT, a ground plane 1 meter × 1.6 meters is placed on top of the 0.8-meter high table. This is known as a horizontal coupling plane (HCP). For the 1992 version (IEC 801-2: 1984), this ground plane is directly referenced to earth ground. For the 1997 version (EN 61000-4-2), this ground plane is referenced to ground through two 470-kW resistors. The EUT is placed 0.1 meter above the ground plane reference table for the 1992 version; the 1997 version requires 0.05 meter.

For floor-standing EUTs, both versions require the EUT to be placed 0.1 meter above the ground plane reference (floor). The 1992 version only needs air discharge to 8 kV, positive polarity. The 1997 version requires contact discharge (to 4 kV) and air discharge (to 8 kV) in both the positive and negative polarities. Only the 1997 version requires the contact discharges to a vertical coupling plane (VCP).

The question arises: Which version makes it easier to meet the ESD requirement? That depends on the design of the product. Normally, you would think the later version is more difficult to comply with. In our experience, we had a product that failed to meet the requirement of the 1992 version, but it met the requirement of the 1997 version.

Radiated RF

Both versions require the radiated, radio-frequency electromagnetic field (Radiated RF) test, but the test setup is different. This is the only test that must be performed in an anechoic or semi-anechoic chamber. The measurement distance for the 1992 version (IEC 801-3) is 1 meter, while the 1997 version (EN 61000-4-3) prefers 3 meters.

During testing, the antenna faces the front side of the EUT for the 1992 version; the 1997 version requires the antenna to face the most sensitive side of the EUT. To meet this requirement, the EUT will be tested with the antenna facing all sides of the EUT, which takes much more time to perform. Using software to control the frequency increment will greatly reduce the test time, since most signal generators have a function of linear increment frequency but not log increments.

Keep in mind that the chamber must be calibrated and a uniform field must be established. This data will be used with the software that operates the test.

The field strength is the same (3 V/m) for both the 1992 and the 1997 versions, but different in modulation. The 1992 version needs an unmodulated field. The 1997 version needs an 80% amplitude modulation with a 1-kHz sine-wave field. The measurement frequency range for the 1992 version is from 27 to 500 MHz while the 1997 version requires a range from 80 to 1,000 MHz. Only the 1997 version needs pulse modulation at 900 ±5 MHz (EN 50204).

Overall, it is more difficult to comply with the requirement of the 1997 version than that of the 1992 version. The measurement frequency range is wider, the modulation is harder, and the 900-MHz range is added for the 1997 version.

EFT

Both versions require the electrical fast transient/burst (EFT) test. The requirements and test setup are the same between both versions. A network is used to couple the test voltage to the power ports, and a capacitive coupling clamp is used for I/O and communication ports of the EUT. Both polarities of the test signal must be applied. During power port testing, the transient signal is coupled onto the phase, neutral, and ground of an IEC AC power port.

If an EUT fails the EFT test to the power port, a power-line filter normally will help solve this problem. For the signal ports, shielded cables and grounding will help. For software-driven EUTs, failures may be overcome by a software reset of the EUT since the performance requirement allows errors during testing with self-recovery.

Surge

Surge test of the input power port is only required by the 1997 version. For an IEC plug, the surges are coupled to phase-to-neutral, phase-to-ground, and neutral-to-ground with 0°, 90°, 180°, and 270° phase angles with respect to the AC power line. The test waveform is 1.2/50 µs (8/20 µs).

The standard requires no more than one surge in a minute, five surges in both the positive and negative polarities for each phase angle, and the surge voltage increased in steps up to the required test level (0.5 kV, 1 kV, 2 kV). It will take five hours and 20 minutes to perform surge testing for an IEC power plug. If the EUT has no slope detection circuitry, to save test time, the 0° or 180° phase angle may be omitted since 0° and 180° phase angles are zero-crossing.

Some surge test instruments include software to control the coupling and phase angles. The test personnel simply sets all the parameters, clicks a start button, and sits back to monitor the test for five hours if there are no failures.

If an EUT fails surge testing and the same unit has been through previous surge tests for several phase angles, a new test sample may help solve the problem. Some components become fatigued after testing and must be replaced. If an EUT contains surge protection circuitry, the EUT should easily meet this requirement.

Conducted RF

The conducted RF test is only required for the 1997 version. It includes the low-frequency range of 0.15 to 80 MHz which is not covered by the radiated RF testing. Testing of power lines and signal lines is required. The signal strength is 3 V, 80% amplitude modulation with a 1-kHz sine wave.

A coupling/decoupling network (CDN) is used for signal injection onto the AC power lines, and an EM injection clamp is used for coupling the test signal onto signal lines. There are several types of CDNs available for use with the test.

The failure rate for this test is about the same as for the radiated RF test. If a failure occurs during testing, the test itself will not cause destructive damage to the EUT as in ESD or surge testing. Normally, a reset of the EUT will bring back normal operation.

Power-Frequency Magnetic Field

The power-frequency magnetic field test is only required by the 1997 version. The EUT is placed in the center of the induction coil. The test requirement states the EUT must be tested in three orthogonal directions. For a relatively small EUT, changing the direction of the EUT will be easier than changing the direction of the induction coil.

The standard requires testing to a magnetic field strength of 3 A/m at 50 Hz. It is easy to meet this requirement. In our experience, we have not seen any product that has failed this test, even when a field strength up to 30A/m is used.

Voltage Dips, Short Interruptions, and Voltage Variations

The voltage-dips, short-interruptions, and voltage-variations test is only required by the 1997 version. The standard (EN 61000-4-11) requires voltage dips at 30% (10 ms) and 60% (100 ms) reduction and voltage interruptions at >95% (5,000 ms) reduction. Since most power supplies have a wide input voltage range of 100 to 240 VAC, the 30% reduction does not affect the function of the EUT. For the 60% and >95% voltage-reduction requirement of the test, the performance criterion is C (temporary loss of function, provided the function is self-recoverable or can be restored by the operator), which means it is easy to meet this requirement.

Summary

So if my product has been tested and meets the EN 50082-1: 1992 requirements, do I need to have the product retested when the EN 50082-1: 1997 version takes effect? The answer is yes.

When deciding which one of the two standards to use, answer these basic questions:

Is this product going to have a short life cycle?

Will this product, including its technology, be in existence when the new requirement (EN 50082-1:1997) becomes mandatory?

If the answer to the first question is yes, test the product to the 1992 generic requirements. This will satisfy the immunity requirements and cost less for laboratory test time. Remember, there are only three immunity tests required for EN 50082-1: 1992.

If the answer to the second question is yes, then test the product to the 1997 generic requirements. This will prevent retesting to the new requirements later.

Keep in mind, if testing a product to the 1992 version and it remains in production past the year 2001, then it will have to be retested. There are seven tests required for EN 50082-1: 1997. The cost of testing will be expensive if the product was tested to both the 1992 and the 1997 requirements. Effective July 1, 2001, the 1992 version no longer will be accepted, and the 1997 version becomes mandatory.

References

EN 50082-1: 1992, Electromagnetic Compatibility—Generic Immunity Standard, Part 1: Residential, Commercial and Light Industry, CENELEC.

EN 50082-1: 1997, Electromagnetic Compatibility—Generic Immunity Standard, Part 1: Residential, Commercial and Light Industry, CENELEC.

EN 50082-2: 1994, Electromagnetic Compatibility—Generic Immunity Standard, Part 2: Industrial Environment, CENELEC.

About the Authors

Michael J. Alvarado is a staff engineer at Intertek Testing Services. Since 1983, he has been involved in compliance engineering in an R&D group and an engineering group testing for U.S. and foreign markets. Mr. Alvarado, who has been at ITS for six years, is a graduate of Orange County Community College, NY, and holds an A.A.S. in electrical engineering. e-mail: [email protected].

Grace Lin is a senior project engineer in Telco Stream, an ITS group that focuses on the telecommunications industry. Ms. Lin has worked in the EMC field since 1984, the last six years at ITS. She graduated from National Taiwan Marine University with a B.S. in electronic engineering and Syracuse University with an M.S. in electrical engineering. e-mail: [email protected].

Intertek Testing Services NA Inc., 4317-A Park Drive, NW, Norcross, GA 30093, (770) 925-2444.

Description	Basic Standard	Test Specification	Performance Criteria
ESD	IEC 801-2: 1984	+8-kV air discharge	B
Radiated RF	IEC 801-3: 1984	27 to 500 MHz, 3V/m unmodulated	A
EFT	IEC 801-4: 1988	±0.5-kV I/O ports, ±0.5-kV DC power ports, ±1-kVAC power ports	B

Table 1.

Description	Basic Standard	Test Specification	Performance Criteria
ESD	EN 61000-4-2: 1995	±4k-V contact discharge ±8-kV air discharge	B
Radiated RF	EN 61000-4-3: 1997	80 to 1,000 MHz, 3V/m, 80% AM w/1-kHz sine wave	A
EFT	EN 61000-4-4: 1995	±0.5-kV I/O ports, ±0.5-kVDC power ports, ±1-kVAC power ports	B
Surge	EN 61000-4-5: 1995	±2-kV line to earth ±1-kV line to line	B
Conducted RF	EN 61000-4-6: 1996	0.15 to 80 MHz, 3 V, 80% AM w/1-kHz sine wave	A
Magnetic Field	EN 61000-4-8: 1993	50 Hz, 3 A/m	A
Voltage Dips and Interruptions	EN 61000-4-11: 1994	30% reduction, 10 ms 60% reduction, 100 ms >95% reduction, 5,000 ms	B C C