ABB RELION 670 Series Technical Manual page 616

Section 9
Voltage protection
Normal voltage
IntBlkStVal1
IntBlkStVal2
ANSI05000466 V1 EN-US
Figure 329: Blocking function
9.1.7.4 Design
The voltage measuring elements continuously measure the three phase-to-neutral voltages or the
three phase-to-phase voltages. Recursive fourier filters or true RMS filters of input voltage signals
are used. The voltages are individually compared to the set value, and the lowest voltage is used
for the inverse time characteristic integration. A special logic is included to achieve the
out of 3 and 3 out of 3 criteria to fulfill the PICKUP condition. The design of Two step undervoltage
protection UV2PTUV (27) is schematically shown in
610
V Disconnection
Pickup1
Pickup2
tBlkUV1 <
t1,t1Min
tBlkUV2 <
t2,t2Min
Block step 1
Block step 2
Figure
Time
en05000466_ansi.vsd
330.
1MRK 502 066-UUS B
M15326-35 v7
1 out of 3 , 2
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