4.170
SEL-700G Relay
Instruction Manual
Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
For example, if SYNCPY := 90 (indicating VS constantly lags VPY = VAY by
90 degrees), but VS actually lags VAY by 100 angular degrees on the power
system at a given instant, the angle difference calculator automatically
accounts for the 90 degrees and:
Angle Difference = |(
VPY –
VS)| = 10°
Also, if breaker close time setting TCLOSDY := OFF, the angle difference
calculator does not take into account breaker close time, even if the voltages
VPY and VS are “slipping” with respect to one another. Thus, synchronism-
check elements 25AY1 or 25AY2 assert to logical 1 if the absolute angle
difference is less than corresponding maximum angle setting 25ANG1Y or
25ANG2Y.
Figure 4.114
Angle Difference Between VPY and VS Compensated by Breaker
Close Time (fPY < fS and VPY Shown as Reference in This Example)
Voltages VPY and VS Are “Slipping”.
Refer to the bottom of
Figure 4.113. If the slip frequency is greater than 0.005 Hz, and breaker close
time setting TCLOSDY
OFF, the angle difference calculator takes the
breaker close time into account with breaker close time setting TCLOSDY
(set in ms; see Figure 4.114). The angle difference calculator calculates the
angle difference between voltages VPY and VS, compensated with the
breaker close time:
Angle Difference = |(
VPY –
VS) + [(fPY – fS) • TCLOSDY
• (1 / 1000) • (360°/slip cycle)]|
Angle Difference
Decreasing (VS* Approaching VPY)
Angle Difference
Increasing (VS* Moving Away From VPY)
Angle
Difference
Angle
Difference
Angle Compensation for
Breaker Close Time
TCLOSDY
Angle Compensation
for Breaker Close Time
TCLOSDY
Setting
25ANG1Y
(or 25ANG2Y)
Setting
25ANG1Y
(or 25ANG2Y)
Setting
25ANG1Y
(or 25ANG2Y)
VPY
VS
VS*
VS*
VPY
VS
Setting
25ANG1Y
(or 25ANG2Y)
Summary of Contents for SEL-700G Series
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