3-36 Overcurrent, Voltage, Synchronism Check, and Frequency Elements Date Code 990430
SEL-351P Manual Técnico
If the voltages are not static (voltages slipping with respect to one another), the two synchronism
check elements operate as shown in the bottom of
Figure SECTION 3: .23. The angle difference
is compensated by breaker close time, and the breaker is ideally closed at a zero degree phase
angle difference, to minimize system shock.
These synchronism check elements are explained in detail in the following text.
Synchronism Check Elements Settings
Table SECTION 3: .9: Synchronism Check Elements Settings and Settings Ranges
Setting Definition Range
25VLO low voltage threshold for “healthy voltage”
window
0.0 - 150.0 V secondary
25VHI high voltage threshold for “healthy voltage”
window
0.0 - 150.0 V secondary
25SF maximum slip frequency 0.005 - 0.500 Hz
25ANG1 synchronism check element 25A1 maximum
angle
0° - 80°
25ANG2 synchronism check element 25A2 maximum
angle
0° - 80°
SYNCP synchronizing phase VA, VB, or VC
TCLOSD breaker close time for angle compensation 0.00 - 60.00 cycles
BSYNCH SEL
OGIC
Control Equation block synchronism
check setting
Relay Word bits referenced
in Table 9.3
Accuracy
Voltage Pickup: ±1 V and ±5% of setting
Voltage Transient Overreach: ±5% of setting
Slip Pickup: 0.003 Hz
Angle Pickup: ± 2 °
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