Schweitzer Engineering Laboratories SEL-700G Series, Инструкция по эксплуатации

Страница: 194 / 824

4.88
SEL-700G Relay Instruction Manual Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
current waveform is highly distorted. This ensures fast operation of the 50Pmn
phase overcurrent elements even with severe CT saturation.
When the harmonic distortion index exceeds the fixed threshold, which
indicates severe CT saturation, the phase overcurrent elements operate on the
output of the peak detector. When the harmonic distortion index is below the
fixed threshold, the phase overcurrent elements operate on the output of the
cosine filter.
The 50Pm3 individual phase overcurrent elements are three single-phase
overcurrent elements with common pickup and delay settings. Figure 2.22
shows a typical application using window CTs for differential protection of
split-phase winding. The individual phase elements facilitate identification of
the faulted phase. If you want individual pickup setting per phase, use
SEL
OGIC
timers and analog quantities (for example, IAY_MAG, IBY_MAG,
and ICY_MAG) to create the necessary elements. See Logic Settings (SET L
Command) on page 4.193 and Table K.1.
The relay offers two types of ground fault-detecting overcurrent elements. The
neutral overcurrent elements (50N1T and 50N2T) operate with current
measured by the input IN. The residual (RES) overcurrent elements operate
with the current derived from each winding phase currents (see Figure 4.53).
Table 4.18 Neutral Overcurrent Settings
Setting Prompt Setting Range
Setting Name :=
Factory Default
NEUT IOC LEVEL OFF, 0.50–96.00 A
a
a
Setting ranges shown are for 5 A nominal CT rating. Divide by 5 for 1 A CT.
50N1P := OFF
NEUT IOC DELAY 0.00–400.00 s 50N1D := 0.50
NEUT IOC TRQCTRL SEL
OGIC
50N1TC := 1
NEUT IOC LEVEL OFF, 0.50–96.00 A
a
50N2P := OFF
NEUT IOC DELAY 0.00–400.00 s 50N2D := 0.50
NEUT IOC TRQCTRL SEL
OGIC
50N2TC := 1