The function starts when the current exceeds the set limit. Each phase has its owntimer. The operating time characteristics for low-stage PH3LPTOC and high-stagePH3HPTOC can be selected to be either definite time (DT) or inverse definiteminimum time (IDMT). The instantaneous stage PH3IPTOC always operates withthe DT characteristic.In the DT mode, the function operates after a predefined operating time and resetswhen the fault current disappears. The IDMT mode provides current-dependenttimer characteristics.The function contains a blocking functionality. It is possible to block functionoutputs, timers or the function itself, if desired.4.1.2.4 Operation principleThe function can be enabled and disabled with the Operation setting. Thecorresponding parameter values are "On" and "Off".The three-phase overcurrent protection PH3xPTOC is used as single-phase and three-phase non-directional overcurrent and short circuit protection. The phase operationmode is selected with the Operation curve type setting. The operation is furtherspecified with the Num of start phases setting, which sets the number of phases inwhich the current must exceed the set current start value before the correspondingstart and operating signals can be activated.The operation of the three-phase overcurrent protection function can be describedusing a module diagram. All the modules in the diagram are explained in the nextsections.Section 4 1YHT530004D05 DProtection functions158 615 seriesTechnical Manual
