ABB RELION 620 Series Technical Manual page 761

1MAC504801-IB E
620 series ANSI
Technical Manual
Difference angle
V_Bus
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Figure 383: 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 V V
(
= ∠ − ∠
Bus
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∠V Measured bus voltage phase angle
Bus
∠V 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 defined
CB
Closing time of CB setting parameter value
with the
The closing angle is the estimated angle difference after the breaker closing delay.
The Minimum Syn time setting time can be set, if required, to demand the minimum time
within which conditions must be simultaneously fulfilled before the SYNC_OK output is
activated.
The measured voltage, frequency and phase angle difference values between the two sides
of the circuit breaker are available as monitored data values V_DIFF_MEAS,
= -
V_Bus V_Line
Difference voltage
V_Line
Live line or bus value
Dead line or bus value
Frequency deviation
f f T
) ( ( ) (
° + − ×
Line Bus line CB
Control functions
Difference frequency
f f f
= -
V_Bus V_Line
f
f
V_Line
V_Bus
Frequency[Hz]
Rated frequency
T
) 360 )
+ × °
PL
Section 9
(Equation 103)
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