ABB 615 Series ANSI, Technical Manual

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Section 7
1MAC050144-MB C
Control functions
524 615 series ANSI
Technical Manual
Figure 288: Angle difference when power transformer is in sychrocheck zone
The vector group of the power transformer is defined with clock numbers, where the value
of the hour pointer defines the low voltage-side phasor and the high voltage-side phasor is
always fixed to the clock number 12 which is same as zero. The angle between clock
numbers is 30 degrees. When comparing phase angles, the V_BUS input is always the
reference. This means that when the Yd11 power transformer is used, the low voltage-side
voltage phasor leads by 30 degrees or lags by 330 degrees the high voltage-side phasor.
The rotation of the phasors is counterclockwise.
The generic rule is that a low voltage-side phasor lags the high voltage-side phasor by
clock number * 30º. This is called angle difference adjustment and can be set for the
function with the Phase shift setting.
7.3.5 Application
The main purpose of the synchrocheck function is to provide control over the closing of
the circuit breakers in power networks to prevent the closing if the conditions for
synchronism are not detected. This function is also used to prevent the reconnection of two
systems which are divided after islanding and a three-pole reclosing.
The synchrocheck function block includes both the synchronism check function and the
energizing function to allow closing when one side of the breaker is dead.
V_Line
V_Bus
M
V_ Bus
V_Line