4.164
SEL-700G Relay
Instruction Manual
Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
Step 7. Calculate a refined 25RCFX setting by dividing VSs by VP:
25RCFX = VSs/VP = __________
Step 8. If the 25RCFX value calculated in Step 7 varies from the
25RCFX setting noted in Step 1, enter the value as a new
25RCFX setting to improve the accuracy of the synchronism-
check voltage acceptance logic.
Synchronism-Checked Supervised Closing.
The 25C, 25AX1, and
25AX2 Relay Word bits are available to supervise the internal Close Logic or
external devices. The most convenient method to apply the synchronism-
check function is to use one of the resulting Relay Word bits in the CLX
SEL
OGIC
control equation, see Figure 4.130 and Figure 4.131 for additional
detail.
Synchronism-Check Elements (Tie Breaker, Y-Side)
Figure 2.26 shows an example of where synchronism check can be applied.
Synchronism-check voltage input
VS
is connected to one side of the circuit
breaker, on any necessary phase. The other synchronizing phase (
VA
,
VB
, or
VC
voltage inputs) on the other side of the circuit breaker is setting selected.
The two synchronism-check elements (25A1Y and 25A2Y) use the same
voltage window (to ensure healthy voltage), frequency window (FNOM +/- 5
Hz), and slip frequency settings (see Figure 4.112 and Figure 4.113). They
have separate angle settings.
If the voltages are static (voltages not slipping with respect to one another) or
setting TCLOSDY := OFF, the two synchronism-check elements operate as
shown in the top of Figure 4.113. The relay checks these angle settings for
synchronism-check closing.
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 4.113. 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.
Содержание SEL-700G Series
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