Undervoltage Protection; Undervoltage Protection Theory - NR Electric PCS-9611 Instruction Manual

3 Operation Theory
12 50/51P4.CLP.IMult
13 50/51P4.CLP.t_Op
14 50/51P4.CLP.TMS
15 50/51G1.CLP.IMult
16 50/51G1.CLP.t_Op
17 50/51G2.CLP.IMult
18 50/51G2.CLP.t_Op
19 50/51G3.CLP.IMult
20 50/51G3.CLP.t_Op
21 50/51G4.CLP.IMult
22 50/51G4.CLP.t_Op
23 50/51G4.CLP.TMS

3.12 Undervoltage Protection

3.12.1 Undervoltage Protection Theory

This relay provides a two-stage undervoltage protection with definite time delay characteristics.
The two stages have same protection logics. Each stage can be used for tripping or alarming
through the PCS-Explorer and the default is for tripping.
This protection can support all kinds of VT connection: three phase voltage (Ua, Ub, Uc), three
phase-to-phase voltages (Uab, Ubc, Uca), two phase-to-phase voltages (Uab, Ubc), anyone of
three phase voltages or anyone of three phase-to-phase voltages.
Two methods are used to check the undervoltage condition by the setting [27P.Opt_1P/3P]. If
setting [27P.Opt_1P/3P] is set as "0", and all of the three voltage values are less than the voltage
setting, the undervoltage protection will operates after the appointed time delay; and if the setting
[27P.Opt_1P/3P] is set as "1", and anyone of the three voltage values is less than the voltage
setting, the undervoltage protection will operates after the appointed time delay.
The setting [27P.Opt_Up/Upp] is used to decide the voltage input mode. If it is set as "1", the input
voltage is phase-to-phase voltage; and if it is set as "0", the input voltage is phase voltage. So the
3-42
The multiple setting of the stage 4 overcurrent
protection when CLP is active
The time setting of the stage 4 overcurrent
protection when CLP is active
The time multiplier setting of the IDMT overcurrent
protection when CLP is active
The multiple setting of the stage 1 zero sequence
overcurrent protection when CLP is active
The time setting of the stage 1 zero sequence
overcurrent protection when CLP is active
The multiple setting of the stage 2 zero sequence
overcurrent protection when CLP is active
The time setting of the stage 2 zero sequence
overcurrent protection when CLP is active
The multiple setting of the stage 3 zero sequence
overcurrent protection when CLP is active
The time setting of the stage 3 zero sequence
overcurrent protection when CLP is active
The multiple setting of the stage 4 zero sequence
overcurrent protection when CLP is active
The time setting of the stage 4 zero sequence
overcurrent protection when CLP is active
The time multiplier setting of the zero sequence
IDMT o vercurrent protection when CLP is active
Date: 2014-04-08
1.00~10.00 0.001
0~100s 0.001s
0.05~100.0 0.001
1.00~10.00 0.001
0~100s 0.001s
1.00~10.00 0.001
0~100s 0.001s
1.00~10.00 0.001
0~100s 0.001s
1.00~10.00 0.001
0~100s 0.001s
0.05~100.0 0.001
PCS-9611 Feeder Relay