Information Technology (IT) Equipment:  EN 55022 & EN 55024

• Overview
• Determining Highest Frequency for Emissions Testing
• Sample Test Matrix
• Technical Notes Concerning I/O Cables
• Miscellaneous Technical Notes
• Scheduling

Overview

Typical equipment falling under this category include desktop computers, laptop computers, file servers, computer peripherals, digital data recording and/or storage devices, etc.

EMC testing for the European Union includes compliance with both emissions and immunity standards.  Emissions from IT equipment are regulated by EN 55022 and immunity is regulated by EN 55024.  As of January 1, 2001, compliance with AC power line harmonics (EN 61000-3-2) and AC power line flicker (EN 61000-3-3) is also required.  These last two standards apply to most single-phase products that connect to the AC power mains and draw less than 16 Amps of current.

In the United States, compliance of Information Technology (IT) equipment with federal requirements is governed by the Federal Communications Commission (FCC).  Limits are defined by the Code of Federal Regulations (CFR) Title 47, Part 15, which regulates the emissions (unintentional and intentional) from a product.

Determining Highest Frequency for Emissions Testing [top of page]

In general, compliance testing for the EU is more stringent than for the U.S. because both emissions and immunity are required.  However, there is one notable exception for IT equipment.  The European standard, EN55022, only regulates unintentional radiated emission levels from a product up to 1 GHz, while the FCC uses the following criteria* for unintentional radiators to determine the highest frequency of measurement:

*information in table taken from CFR 47, Part 15

Other countries have also adopted EMC standards as part of their agency requirements.  While these countries’ typically require the same emission limits as EN 55022, there are a number of logistical details which need to be addressed for compliance.  Contact EMC Integrity for more information.

Sample Test Matrix [top of page]

A typical test matrix for an ITE product for compliance with both EU and FCC requirements is contained in the table below.

Technical Notes Concerning I/O Cables [top of page]

Approximately 80% of EMC compliance issues are related to cables.  Power and I/O cables create the “antenna structure” for a product.  These unintentional antennas can both radiate electromagnetic energy generated by electronics inside the product and receive electromagnetic energy impinged upon the product.  The former could result in non-compliance with regard to emissions and the latter could create an immunity problem.

Since cables are an integral part of a product’s function and configuration, clients should realize some significant factors about cables prior to testing for EMC compliance.

• For emissions testing, all I/O ports (excluding service or maintenance) should be loaded with a cable of at least 1 meter in length, per ANSI C63.4
• For immunity testing, if a cable can be greater than 3 meters in length, electrical fast transient testing via capacitive clamp applies to this cable
• Non conductive cables (e.g., fiber optic or plastic tubes) are exempt from cable testing requirements

Miscellaneous Technical Notes [top of page]

Note 1.   Whether a product is tested to Class A or Class B limits for emissions depends on where it will be used.  If a product may be used in a residential environment, it should meet the Class B limits, which are 10 dB more stringent than Class A.  If a product will only be used in commercial, office or industrial environments, the Class A limit then applies.

Note 2.   When measuring the radiated E-field emissions for both U.S. and EU compliance, this test should be performed at the European voltage of 230 Vac/50 Hz.  The FCC will accept radiated emissions data taken at this voltage, but the inverse is not true.  Conducted emissions testing should be performed at both U.S. and European voltage and frequency inputs.

Note 3.   When performing immunity testing, keep in mind that the product will need to be monitored to ensure that its level of performance meets the requirement defined for the test being performed.  Different tests have different performance criteria, which are summarized as follows:

Level A:    The equipment shall continue to operate as intended without user intervention.

Level B:     After the test, the equipment shall continue to operate as intended without user intervention.

Level C:     Loss of function is allowed, provided that the product can be restored by the operation of controls (i.e., no permanent damage).

The performance criterion for each immunity test is listed in the following table.

Scheduling [top of page]

EMC Integrity generates a detailed quotation for all formal compliance testing that we perform.  Our quotations state the name of the product to be tested, the standards to which the product will be tested, the individual tests that will be performed and any additional testing that may be requested by the client.  Tests are listed on a line-item basis, thus clearly delineating both the scope of work and the cost of each test.  An outline of our process is given below.

Overview of EMCI’s RFQ Process.