Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

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SEL-700G Relay Instruction Manual Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
through time. Synchronism-check element 25AY1 or 25AY2 asserts to logical
1 for either one of the following scenarios.
1. The top of Figure 4.114 shows the angle difference
decreasing—VS* is approaching VPY. When VS* is in phase
with VPY (Angle Difference = 0 degrees), synchronism-check
elements 25AY1 and 25AY2 assert to logical 1.
2. The bottom of Figure 4.114 shows the angle difference
increasing—VS* is moving away from VPY. VS* was in phase
with VPY (Angle Difference = 0 degrees), but it has now
moved past VPY. If the angle difference is increasing, but the
angle difference is still less than maximum angle settings
25ANG1Y or 25ANG2Y, then corresponding synchronism-
check elements 25AY1 or 25AY2 assert to logical 1.
In this scenario of the angle difference increasing, but where it
is still less than maximum angle settings 25ANG1Y or
25ANG2Y, the operation of corresponding synchronism-check
elements 25AY1 and 25AY2 becomes less restrictive.
Synchronism-check breaker closing does not have to wait for
voltage VS* to slip around again in phase with VPY (Angle
Difference = 0 degrees). There might not be enough time to
wait for this to happen. Thus, the “Angle Difference = 0
degrees” restriction is eased for this scenario.
Synchronism-Check Applications for Manual Closing
Refer to Figure 4.130 for additional detail.
SEL-700GT can be applied for synchronism-check supervised closing of
breaker 52Y.
EXAMPLE 4.4 For Manual Closing by Input IN302 Set
CLY := … OR SV12T AND 25AY1
SV12 := R_TRIG IN302
SV12PU := 0.00
SV12DO := as necessary
The SV12DO defines a time window for the supervising Relay Word bit
(25A1Y) to assert for a successful closing.