1. For a particular value of Beta the third harmonic neutral voltage is measured with the
generator in the no-load condition and the circuit breaker in the closed position.
2. With the same condition, the third harmonic neutral voltage with the circuit breaker
in the open position is measured.
3. CB Open factor should be set equal to the ratio of the third harmonic neutral voltage
measured with the circuit breaker in the closed position to that in the open.
4.2.7.6 Signals
Table 407: 27/59THN Input signals
Name Type Default Description
V_3H_A SIGNAL 0 Third harmonic of phase A voltage
V_3H_B SIGNAL 0 Third harmonic of phase B voltage
V_3H_C SIGNAL 0 Third harmonic of phase C voltage
V_3H_N SIGNAL 0 Third harmonic of neutral voltage
V_3H_RES SIGNAL 0 Third harmonic of residual voltage
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
GCB_CLOSED BOOLEAN 0=False Generator CB in closed position
Table 408: 27/59THN Output signals
Name
Type Description
TRIP BOOLEAN Trip
PICKUP BOOLEAN Pickup
INT_BLKD BOOLEAN Protection internally blocked
4.2.7.7 Settings
Table 409: 27/59THN Group settings (Basic)
Parameter
Values (Range) Unit Step Default Description
Beta 0.50...10.00 0.01 3.00 Portion of neutral side 3rd harmonic used as
bias
Voltage N 3.H Lim 0.005...0.200 xUn 0.001 0.010 Pickup value for 3rd harmonic residual
undervoltage protection
Trip delay time 20...300000 ms 10 20 Trip delay time
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 435
Technical Manual
To Next Page
Loading...
