What is EFT (Electric fast transient)?

Issuing time:2015-01-15 18:26

The electric fast transient (EFT) is caused in electric circuit, when break the inductive load, at the point of disconnection will cause transient disturbance because of contactor clearance insulation breakdown or jumping, if the inductive load repeat switch on and off, then the pulse burst will repeat. Generally, the power of transient disturbance is small, will not cause the damage, but because of the wide spectral distribution, it will affect the reliability of electric and electronic equipment. The purpose of EFT test is to check the equipment’s performance under EFT influence. The EFT test is to coupling the pulse burst to power port, signal port and control port. The key point for this test is rise time, repetitive rate and low power. Thus, the test is applied to the equipment powered by AC supply network, equipment powered by long DC power cable, and signal ports and controls ports of equipment (because the long AC/DC power cable and signal control cable can be affected by EFT which caused by the equipment around). Meanwhile, the other devices powered by the same public AC/DC supply network will cause the EFT, and then affect the device.


The target of EFT test is power port, signal port, control port and grounding port, the purpose for EFT test is to set up a common and repeatable criterion. According to IEC61000-4-4 standard, there are several test grades for EFT test as table 1. Combine with lighting industry, EFT test is applied to lighting device, like EN61547 Equipment for General Lighting Purpose-EMC immunity requirements clause 5.5, it mentions the request for EFT test. The test grade for general lighting device is as table 2.


Table 1:



Table 2:


There are 4 test results for EFT test. 1) Normal performance within limits specified by the manufacturer, requestor or purchaser. 2) Temporary loss of function or degradation of performance which ceases after the disturbance ceases, and from which the equipment under test recovers its normal performance, without operator intervention. 3) Temporary loss of function or degradation of performance, the correction of which requires operator intervention. 4) Loss of function or degradation of performance which is not recoverable, owing to damage to hardware or software, or loss of data.


According to IEC61000-4-4, EN61000-4-4 and GBT17626.4 standards, Pego Group research and developed the EFT61000-4 EFT immunity measurement. This equipment consists by EFT generator and coupling and decoupling network. The max output voltage is 5KV, repetition frequency range is 1 KHz to 1000 KHz adjustable, and completely meet the 4 test grades requirements of IEC61000-4-4, and reserve the space for open grade.


Pego is professional on testing equipment, and engaged in finding the right products and providing the right solutions for the user. If you have any request, please contact Pego to get more information.

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