FANOX SIA-B Series User Manual

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FANOX SIA-B Series User Manual Manual pdf 22 page image

www.fanox.com Rev. 07 22/138The Time Delay is completely independent from the operating current that flows through the relay, so ifthe neutral current exceeds its predetermined value for an equal or greater amount of time than this pre-set value, the protection function activates (trips) and does not reset itself until the value of the phasedrops below the point of current pick-up.When the Function Enable is set to “YES”; the accuracy of the Time Delay is equal to the pre-set time±30 ms or ±0.5% (whichever is greater). If the Function Enable is set to “SHB”, the accuracy of the TimeDelay is equal to the pre-set time ±50 ms or ±0.5% (whichever is greater).The function activates at 100% of the pre-set input and deactivates at 90%. The reset is instantaneous.4.6. Function 50/51G. Inverse time neutral overcurrentThis protection function can be set by using the following parameters:Function Description Minimum Maximum Step Unit Default50/51G Inverse time neutral overcurrentFunction Enable - - Yes/No/SHB - NoCurve type - - (1*) - IEC ExtremelyInverseTime Dial (TMS) 0.01 1.5 0.01 - 1.25Current Tap 0.05 7.00 0.01 xIn 0.50Time Delay 0.02 300.0 0.01 s 0.20(1*) IEC Inverse, IEC Very inverse, IEC Extremely inverse, IEC Long time inverse, Defined time, IEEEInverse, IEEE Very inverse, IEEE Extremely inverseIf the option “Defined time” is selected for the curve setting, the unit behaves like an instantaneousovercurrent unit. In this case, when the Function Enable is set to “YES”; the accuracy of the Time Delayis equal to the pre-set time ±30 ms or ±0.5% (whichever is greater). If the Function Enable is set to“SHB”, the accuracy of the Time Delay is equal to the pre-set time ±50 ms or ±0.5% (whichever isgreater). In this case, the function is activated at 100% of the set tap value, and it deactivates at 95%.If a curve (inverse, very inverse or extremely inverse) is selected for the curve setting, the trip timedepends on the curve, time dial and current tap settings. When the Function Enable is set to “YES”; theaccuracy of the trip time is equal to the theoretical trip time ±30 ms or ±5% (whichever is greater). If theFunction Enable is set to “SHB”, the accuracy of the trip time is equal to the theoretical trip time ±50 msor ±5% (whichever is greater). In this case, the function is activated at 110% of the set tap value, and itdeactivates at 100%.Instantaneous reset in both cases.The curves used are IEC 60255-151 and IEEE, which are described in their section.