issue: August 2008 APPLIANCE Magazine
Safety Compliance Testing
Household Appliances Require Safety Compliance, Too
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by Dieter Baldamus, senior EMC engineer, TÜV Rheinland, North American division
Appliance manufacturers should not forget that, per the international standard EN 60335-1, European household appliances and similar electrical equipment also require EMC testing for safety compliance.
As of October 1, 2007, Amendment 1 of EN 60335-1 became mandatory, making additional EMC testing a requirement for some household and similar electrical equipment.
In general, these electrically operated devices have to comply with the immunity standard CISPR 14-2 (EN 55014-2) and with multiple emissions standards, including: CISPR 14-1 (EN 55014-1), IEC 61000-3-2 (EN 61000-3-2), and IEC 61000-3-3 (EN 61000-3-3).
More and more of these devices have electronic-sensitive components that control the equipment’s safety features. So Amendment 1 of EN 60335-1 incorporated additional EMC tests to verify their safety when the equipment is subjected to electromagnetic interference.
What Appliances Must Comply?
Not all household and similar electrical equipment have to comply with these tests. As described in section 19.11 of the standard, only appliances incorporating a protective electronic circuit are subject to these tests. The definition of a protective electronic circuit is provided in clause 3.9.3 in Amendment 1 of IEC/EN 60335-1:2002.
According to the definition, the protective electronic circuit is an “electronic circuit that prevents a hazardous situation under abnormal operating conditions. Parts of the circuit may also be used for functional purposes.”
In general, the appliances that incorporate electronic controls with sensing and responsive circuits (used for safety reasons) are subject to the tests of clause 19.11.4. In other words, where the protection against a hazardous situation under abnormal operating conditions does not rely on the operation of fuses, circuit breakers, thermal cutouts, thermal fuses, etc., but on the operation of electronic circuits, such appliances must be tested according to clause 19.11.4.
There is a wide range of appliances that can rely on proper operation of protective electronic circuits, for example: garage door operators, kitchen appliances, battery chargers, spas, and other motor-operated, heating, and combined appliances.
Additionally, appliances having a switch with an off position obtained by electronic disconnection, or a switch that can be placed in the standby mode, are subjected to the test of clause 19.11.4.
During and/or after the testing according to clause 19.11.4, compliance with the standard requirements is verified according to clause 19.13.
The test levels required for safety compliance are higher than the ones required under the CISPR 14-2 standard and are carried out after the electronic protective circuit has operated during the relevant test of abnormal operation described in clause 19. The levels and basic standards are:
- Electrostatic Discharge in accordance to IEC 61000-4-2, level 4(±8 kV Contact Discharge, ±15 kV Air Discharge). Ten discharges having a positive polarity and 10 discharges having a negative polarity are applied at each preselected point (section 18.104.22.168 of the standard).
- Electromagnetic Field Immunity test in accordance to IEC 61000-4-3 level 3 (10 V/m), with a dwell time for each frequency sufficient to observe a possible malfunction of the protective electronic circuit (section 22.214.171.124 of the standard).
- Electrical Fast Transients test in accordance with IEC 61000-4-4, level 3 (±2 kV) for signal and control lines and level 4 (±4 kV) for power supply lines. The burst shall be applied 2 minutes at each polarity (section 126.96.36.199 of the standard).
- Surge Immunity in accordance to IEC 61000-4-5, five positive and five negative discharges at level 3 (±2 kV) coupled between each power line, and five positive and five negative discharges at level 4 (±4 kV) coupled between each line and ground. This section has some considerations regarding heating elements and surge arresters (section 188.8.131.52 of the standard).
- Conducted Immunity test in accordance to IEC 61000-4-6 (10 V rms) and between 0.15 and 80 MHz, with a dwell time for each frequency sufficient to observe a possible malfunction of the protective electronic circuit (section 184.108.40.206 of the standard).
- Voltage Dips and Interruptions in accordance with IEC 61000-4-11, with dips and interruptions specified in Table 1 of the standard, which are:
- 0% during one cycle, at zero crossing of the supply voltage.
- 40% during 10 cycles (if appliance runs at 50 Hz) or 12 cycles (if appliance runs at 60 Hz) and at zero crossing of the supply voltage.
- 70% during 25 cycles (if appliance runs at 50 Hz) or 30 cycles (if appliance runs at 60 Hz) and at zero crossing of the supply voltage.
- 80% during 250 cycles (if appliance runs at 50 Hz) or 300 cycles (if appliance runs at 60 Hz) and at zero crossing of the supply voltage.
- Harmonics and Interharmonics Immunity test in accordance to IEC 61000-4-13, test level class 2 as described in the standard.
In general, it is expected that the appliance shall not undergo a dangerous malfunction and there shall be no failure of protective electronic circuits if the appliance is still in operation.
An appliance tested with an electronic switch in the off position, or in standby mode, shall not become operational.
About the Author
Dieter Baldamus has 17 years of experience in electromechanical compliance testing and engineering for a variety of electronic products. Baldamus has been a senior EMC engineer with TÜV Rheinland’s North American division in Newtown, CT, U.S. since 1999. Previously, Baldamus was an EMC engineer at Sony International’s product compliance department in Germany where he performed EMC tests of mainly audio and video products. Baldamus holds a BS degree in electrical and electronic engineering from the National Autonomous University of Mexico in Mexico City. Born in Mexico City, Baldamus is fluent in three languages: English, Spanish, and German. The EMC and product safety departments at TÜV Rheinland are capable of performing and evaluating these tests at the required levels to show continuous compliance of household and similar equipment in accordance to the new amendment 1 of the EN 60335-1 standard.