Application Guide - NP900 Series
304 (504
)
A996A
Figure 3.4.6-148 Simplified function block diagram of the SEF function.
3.4.6.1
M
EASURED INPUT VALUES
Function block uses analog voltage measurement values for third harmonic voltage
measurement and three phase current measurement for positive sequence current
blocking. -20ms averaged value is used for pre-fault data registering.
Table 3.4.6.1-202 Measurement magnitudes used by the SEF function.
Signal
Description
Time base
3
rd
.Harm.Voltage
3
rd
.Harm.Voltage
5 ms
3.4.6.2
P
ICK
-
UP CHARACTERISTICS
Function has an inbuilt low current blocking feature to prevent faulty trips. It is set by
parameter Low current blocking I1< set. If this parameter is set above zero measured
positive sequence current must be over the set limit so that the function will trip.
Pick-up of the SEF function is controlled by Pick up setting U03h< set
setting parameter,
which defines the minimum allowed measured neutral third harmonic voltage before
action from the function. The function constantly calculates the ratio in between of the
Uset< and measured magnitude. Reset ratio of 103% is inbuilt in the function and is
always related to the Uset<
value.
Содержание NP900 Series
Страница 1: ......
Страница 49: ...Application Guide NP900 Series 49 504 A996A Figure 3 2 1 3 25 Definite time operating characteristics...
Страница 50: ...Application Guide NP900 Series 50 504 A996A Figure 3 2 1 3 26 IEC predefined characteristics NI VI LTI and EI...
Страница 52: ...Application Guide NP900 Series 52 504 A996A Figure 3 2 1 3 28 IEEE predefined characteristics EI MI and VI...
Страница 243: ...Application Guide NP900 Series 243 504 A996A Figure 3 3 2 1 122 NPS biased thermal trip curves with kNPS values 7 and 10...
Страница 491: ...Application Guide NP900 Series 491 504 A996A 3 7 5 6 SETTING EXAMPLE...
Страница 504: ...Application Guide NP900 Series 504 504 A996A A996A...