ABB RELION REX640 Technical Manual page 1395

1MRS759142 C
REX640
Technical Manual
Difference angle
U_Bus
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Figure 740: Conditions to be fulfilled when detecting synchronism between
systems
When the frequency, phase angle and voltage conditions are fulfilled, the duration of
the synchronism conditions is checked so as to ensure that they are still met when the
condition is determined on the basis of the measured frequency and phase difference.
Depending on the circuit breaker and the closing system, the delay from the moment
the closing signal is given until the circuit breaker finally closes is about 50...250 ms.
The selected Closing time of CB informs the function how long the conditions have to
persist. The Synchro check function compensates for the measured slip frequency and
the circuit breaker closing delay. The phase angle advance is calculated continuously
with the formula.
Closing angle = ∠ U
(
Bus
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∠ U Measured bus voltage phase angle
Bus
∠U Measured line voltage phase angle
Line
f Measured bus frequency
Bus
f Measured line frequency
line
T Total circuit breaker closing delay, including the delay of the protection relay output contacts
CB
Closing time of CB setting parameter value
defined with the
T Output type dependent delay according to
PL
Table 1345: Typical delays for different output types
Output type
Semiconductor output (HSO, SPO)
Mechanical relay output (POSP, PODP, PO)
The closing angle is the estimated angle difference after the breaker closing delay.
= -
U_Bus U_Line
Difference voltage
U_Line
Live line or bus value
Dead line or bus value
Frequency deviation
U f f
) ( ( )
− ∠ ° + − ⋅
Line Bus line
Table 1345
Recommended value for T
0 ms
6 ms
Section 9
Control functions
Difference frequency
f f f
= abs( -
U_Bus U_Line
f
f
U_Line
U_Bus
Frequency[Hz]
Rated frequency
T T
360
( ) )
+ ⋅ °
CB PL
PL
)
(Equation 317)
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