Sel 751A - Figure 4.22 Angle Difference between VP and VS Compensated by Breaker Close Time (Fp < Fs and VP Shown as Reference in this Example)

4.39
Date Code 20100129 Instruction Manual SEL-751A Relay
Protection and Logic Functions
Voltage-Based Protection
Figure 4.22 Angle Difference Between VP and VS Compensated by Breaker
Close Time (fP < fS and VP Shown as Reference in This Example)
Voltages VP and VS Are “Slipping”. Refer to bottom of Figure 4.21. If the
slip frequency is greater than 0.005 Hz and breaker close time setting
TCLOSD ≠ OFF, the Angle Difference Calculator takes the breaker close time
into account with breaker close time setting TCLOSD (set in ms; see
Figure 4.22). The Angle Difference Calculator calculates the Angle
Difference between voltages VP and VS, compensated with the breaker close
time:
Angle Difference = |(∠VP – ∠VS) + [(fP – fS) • TCLOSD • (1 / 1000) •
(360°/slip cycle)]|
Angle Difference
Decreasing (VS* Approaching VP)
Angle Difference
Increasing (VS* Moving Away From VP)
Angle
Difference
Angle
Difference
Angle Compensation for
Breaker Close Time
TCLOSD
Angle Compensation
for Breaker Close Time
TCLOSD
Setting
25ANG1
(or 25ANG2)
Setting
25ANG1
(or 25ANG2)
Setting
25ANG1
(or 25ANG2)
VP
VS
VS*
VS*
VP
VS
Setting
25ANG1
(or 25ANG2)