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Start by
Sergio Feitoza
09-17-2013 01:52 PM

An IEC standard is missing to enable cheaper products

Laboratory type testing is not necessarily the only way to verify if switchgear or other substation equipment attends an IEC or IEE specification. High power tests like the internal arc tests, temperature rise test and short time withstand current test are onerous and time consuming. There are few laboratories in the World with capacity to do them. A user needs to wait several months to do a test. In most of the countries there are no high power laboratories available. Testing simulation techniques are used to predict results of type tests and to obtain more complete information than the information obtained in testing laboratories. For poor countries which will never construct 50 million dollars testing laboratory the “certification of products” via testing simulations is much better than doing nothing.

The main barrier to use simulations to replace tests is that there is no IEC standard specifying the basic rules for that. Also, some important parameters to compare test results with simulation results are not requested in several key IEC technical standards and consequently not measured during laboratory tests. So, frequently you know how to simulate the test but you do not have laboratory test reports complete enough to compare and to validate the simulations.

As an example, the overpressure measurement is not requested during internal arc tests and the measurement of the air temperature inside the enclosure is not requested in some temperature rise tests. In the temperature rise tests it is not requested to register the ohmic resistance of circuit breakers, switches and fuses. As they are the higher power dissipation sources there an obvious opening for using during the test a resistance different from the actual one. So, some tests specified in IEC standards are simply not reproducible because key factors are not registered in the test reports.

There is an open door to have cheaper electric products in worldwide level. The way is to create an IEC standard “Guidelines for the use of simulations and calculations to replace some tests specified in IEC standards”.
09-17-2013 04:49 PM
Top #2
Spir Georges GHALI
09-17-2013 04:49 PM
Dear Mr. Sergio ;

It's too nice what you talk about, Certainly, there's many way to do some tests on Circuit Breakers, but do you think that are enough ? Please let me draw your attention to 2 points only of many others :

1- For small circuit breakers we can do the test of Magnetic protection behavior by using " Injection Current Apparatus ", and suppose the CB's results were good, do you think it's enough ? I'm sure not, because by this apparatus we can inject the necessary current with a very low voltage value ( 5-15V ), so, do you think that the arc will be the same if we have the same current but with " 400V " ?

2- The same question for " Short Circuit Tests " ????

Personally, I done the tests of many MCBs for different manufactures by using " Injection Current Apparatus ", and I saw the same tests in laboratory in France for the same MCBs by injection the same currents values with 230V or 400V depending on the CB, be sure, the results weren't the same, we found some differences for Magnetic protection tests, and big differences for Short Circuit tests
09-17-2013 07:38 PM
Top #3
Sergio Feitoza
09-17-2013 07:38 PM
Dear Spin
Simularions are very useful and have many aplications but not for breking tests in circuit beakers and fuses. These ones require extremely sophisticated models which are not recomended to replace tests
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