Smart earth leakage protection - Circutor

Industrial earth leakage protectionHigh-frequency currentThe IEC 479-1 / UNE 20-572-92 Standarddescribes the effects of currentspassing through the human body fora frequency of 50 Hz. As you can see,the effect depends on the root-meansquare-valueof the current passingthrough the body and the time it takesto pass through. In accordance with theeffects, we can establish zones 1 (zonewith no perception) and 2 (perceptionzone) as safe work zones. Therefore, interms of the protection of persons, earthleakage protection systems must act onthose zones.previous graph, which indicates that thecurrent is less dangerous.See the tableattached, in accordance with IEC 479-2/ UNE 20-572-93, where a fault currentof, for example, 45 mA at 500 Hz has thesame effect as a fault current of 30 mAat 50 Hz. In the case of receivers withEMI filters, we can consider that theseinject a high-frequency earthed current(>2 kHz) and a low frequency current.The use of type A earth leakage protectionsystems is specified in these cases.Frequency factor F fFrequency fWhen the frequency increases, thecurves are displaced to the right of thea. Perception thresholdb. "No-drop" thresholdc1 / c2 / c3. Fibrilation thresholdDelay time1. No perception2. Perception3. Reversible effects. Muscle tetany4. Potentially irreversible effectsSensitivityAdjustments of I ∆n100 % I ∆nThe IEC 61008-1 Standard specifiesthat earth leakage switches must betriggered when the fault earthed currentis between 50% and 100% of the sensitivityvalue (I ∆n) selected. This meansthat the values that exceed 50% canset off the earth leakage switch trigger.This type of case is common withelectromechanical switches. In the caseof electrical energy installations, thesehave evolved in such a way that the adjustmentof protection can cause greatproblems, since it is too low. The electronicearth leakage protection systemsoffered by CIRCUTOR determine thetrigger near 100 % of I ∆n.Therefore, we have a lower risk of triggersand less interruptions in the installation'ssupply than when the fault currentis lower than I ∆n.The following graphs show that with anidentical evolution of the fault earthedcurrent in the same installation, the behaviourof the earth leakage switch isdifferent, even when the sensitivity levelof I ∆nis the same in both cases.This adjustment of I ∆nallows us to concentratemore loads that incorporateearthed capacitors within the same linebeing protected. For example, in a computerinstallation: Each unit diverts acurrent, I leakage, of 2 mA through the EMIfilter capacitors included. At a sensitivityof (I ∆n) 30 mA, you can install 7 computerswith the electromechanical earthleakage switches. However, if you useCIRCUTOR's electronic switches youcan install a total of 12.Fault earthed current I dFault earthed current I d50 % I ∆nTime, t100 % I ∆n85 % I ∆nTime, tP1-7