Electromagnetic compatibility testing in EMC lab
EN 61000 – 4–2:2009 Electromagnetic compatibility (EMC)–Part 4–2: Testing and measuring techniques– Electrostatic discharge immunity test (IEC 61000–4–2:2008)
Analog: IEC 61000 – 4-2:2008 Electromagnetic compatibility (EMC)-Part 4 – 2: Testing and measuring techniques– Electrostatic discharge immunity test.
International standard EN 61000 – 4-2:2009 defines susceptibility requirements regarding Electrostatic Discharge (ESD). This standard defines test setups, environment and test levels for electrical and electronic equipment testing, that is subjected to ESD from user directly or indirectly.
This standard should be used together with generic standards or specific product standards as EN 61000 – 4-2:2009 does not provide specific information on particular equipment testing.
Static charge is an unbalanced electrical charge at rest. Typically, it is created by insulator surfaces rubbing together or pulling apart. One surface gains electrons, while the other surface loses electrons. This results in an unbalanced electrical condition known as static charge. When a static charge moves from one surface to another, it becomes ESD. ESD is a miniature lightning bolt of charge that moves between two surfaces that have different potentials. It can occur only when the voltage differential between the two surfaces is sufficiently high to break down the dielectric strength of the medium separating the two surfaces. When a static charge moves, it becomes a current that damages or destroys gate oxide, metallization and junctions. ESD test is carried out in two ways:
- Contact discharge (preferred method)- method of testing in which the electrode of the test generator is kept in contact with the EUT or coupling plane and the discharge is actuated by the discharge switch within the generator;
- Air discharge– method of testing in which the charged electrode of the test generator is moved towards the EUT until it touches the EUT;
International standard EN 61000 – 4-2:2009 prefer the following test levels and voltage ranges. Detailed test level selection is defined in generic standards and specific product standards.
Applied contact discharge ESD pulse waveform is characterised using current. Current waveform parameters should fit requirements defined in table.
Floor is covered with grounded metallic sheet– ground plane. Table (height 0.8m) is covered with horizontal coupling plane– HCP. Horizontal coupling plane is connected to ground plane using two 470Ohm resistors. Vertical coupling plane (VCP) (0.5m x 0.5m) is located on table. Vertical coupling plane is connected to ground plane using two 470Ohm resistors. Device under test is placed on table on 1mm insulation sheet.
If device under test is floor standing equipment, floor standing test setup should be used. Device under test should be located on 10cm insulation support above ground plane on floor. Vertical coupling plane– VCP, should be connected to ground plane using two 470Ohm resistors.
Application of direct ESD pulses
Contact discharge is applied to conductive surfaces and points or surfaces and points covered by nonconductive layer, that is not used as insulation. Air discharge is applied to all other points and surfaces.
ESD pulses are applied to those points which are accessible by persons under normal use (unless stated otherwise by generic or specific product standards). ESD pulses are not applied to:
- points and surfaces that are accessible during maintenance;
- points and surfaces accessible under service;
- points and surfaces that are not accessible after final installation;
- connector pins that are protected by metallic shell;
- connector contacts and other accessible parts that are ESD sensitive due to functional reasons and are provided by ESD warning label.
Application of indirect ESD pulses
Indirect ESD pulses are applied to horizontal coupling plane and vertical coupling plane. Contact discharge is used. Vertical coupling plane is located in 10cm distance from equipment under test.
The tests results are classified in terms of loss of function or degradation of performance. International standard EN 61000 – 4-2:2009 does not define Pass/Fail criteria. This is defined by generic or specific product standards. EN 61000 – 4-2:2009 defines performance criteria that can be used to evaluate equipment under test performance.
Performance criterion A
Normal performance within limits specified by the manufacturer;
Performance criterion B
Temporary loss of function or degradation of performance. Self-recovery after the test, without operator intervention;
Performance criterion C
Temporary loss of function or degradation of performance. Operator intervention needed for recovery after the test;
Performance criterion D
Loss of function or degradation of performance which is not recoverable. Damage
of hardware or software, or loss of data.