ABB RED615 Technical Manual page 688

Section 9
Control functions
682
In case Syncro check mode is set to "Asyncronous", the additional conditions must
be fulfilled.
• The measured difference of the voltages is less than the set value of Difference
voltage.
• The measured difference of the phase angles is less than the set value of
Difference angle.
• The measured difference in frequency is less than the set value of Frequency
difference.
• The estimated breaker closing angle is decided to be less than the set value of
Difference angle.
Difference angle
U_Bus
GUID-191F6C44-7A67-4277-8AD1-9711B535F1E1 V2 EN
Figure 364: 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.
= -
U_Bus U_Line
Difference voltage
U_Line
Live line or bus value
Dead line or bus value
Frequency deviation
1YHT530004D05 D
Difference frequency
f f f
= abs( - )
U_Bus U_Line
f
f
U_Line
U_Bus
Frequency[Hz]
Rated frequency
615 series
Technical Manual