Electromagnetic compatibility testing in EMC lab
EN 61000–4–11:2003 Electromagnetic compatibility (EMC) — Part 4 – 11: Testing and measurement techniques — Voltage dips, short interruptions and voltage variations immunity tests
Replace: EN 61000 – 4-11:1994 + A1:2001 Electromagnetic compatibility (EMC) — Part 4 – 11: Testing and measurement techniques — Voltage dips, short interruptions and voltage variations immunity tests
Analog: IEC 61000 – 4-11:2004 Electromagnetic compatibility (EMC) — Part 4 – 11: Testing and measurement techniques — Voltage dips, short interruptions and voltage variations immunity testsScope
International standard EN 61000 – 4-11:2004 defines immunity test methods and recommended test levels for electric and electronic equipment connected to low voltage AC mains networks for voltage dips, short interruptions and voltage variations. Requirements are applicable to equipment with rated current up to 16A in 50Hz or 60Hz network.
Since disturbances in the mains voltage are common place and they can interfere with every kind of electrical and electronical system that operates from the mains network it is mandatory to test all electrical equipment that can be connected to mains network.
Dips are short term reductions in supply voltage caused by load switching and fault clearance in the mains supply network. They can also be caused by switching between the mains and alternative supplies. Dips are specified by their reduction below nominal mains voltage and their duration in milliseconds or number of cycles. A dip of 40% is equivalent to a reduction of supply voltage to 60% of its nominal value.
Short voltage interruption is a 95%-100% dip that lasts at least few seconds. Shor voltage interruptions are caused by load switching between mains and an alternative supply.
Electromechanical devices like relays, contactors, solenoids can change their state. Discharge lamps often won’t re-illuminate for a minutes after a short mains interruption.
International standard EN 61000 – 4-11:2004 defines recommended test levels for various equipment classes, but specific test levels should be picked up from generic standards or product standards.
Shot voltage interruption
A dip of 40% is equivalent to a reduction of supply voltage to 60% of its nominal value.
Voltage interruption of 0% is equivalent to a reduction of supply voltage to 100% of its nominal value.
Electromagnetic environment classes are defined as follows:
Class 1: It applies to protected power supplies with compatibility levels lower than public network level. It is applicable to very disturbance sensitive equipment in terms of supply voltage– instrumentation in laboratories, automation and protection equipment, computers caring out critical work load;
Class 2: it applies to point of common coupling for consumer systems and in-plant point f common coupling in the industrial environment in general;
Class 3: It applies to in-plant common coupling points in industrial environments;
The tests results are classified in terms of loss of function or degradation of performance. International standard EN 61000 – 4-11:2004 does not define Pass/Fail criteria. This is defined by generic or specific product standards. EN 61000 – 4-11:2004 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.
The manufacturer’s specification may define effects on the EUT which may be considered insignificant, and therefore acceptable.