[7sj62-64-iefger-logik-20120611, 1, en_US]
Figure 2-89
Logic diagram of the directional intermittent ground fault protection
Direction Determination
The ground fault is detected by evaluating the fundamental component of the displacement voltage. The
sensitivity is determined using the settable threshold value Vgnd> / 3V0>. Direction determination is started
after the ground fault has been detected. For this purpose, the igniting current pulses are extracted from the
ground current signal. The igniting current pulse and the associated maximum displacement voltage over time
are compared with regard to their phase relationship. The fault direction forward or reverse is derived from
this comparison. Each detected ignition pulse receives a direction information. If no clear direction determina-
tion is possible, the direction information pertaining to the pulse is undefined. The direction results of the
recurring ignition pulses are counted and are available as value indication if their value is different than zero.
Pickup
The setting of parameter Pickup defines under which conditions pickup is detected and fault recording
started. For with with Vgnd/3V0>, pickup is initiated once the threshold Vgnd> / 3V0> has been
exceeded. For with oper. dir., pickup is initiated when a pulse is detected in the direction specified at
Functions
2.14 Dir. Intermittent earth fault protection
206 SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
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