Application - ABB RELION Series Technical Manual

1MRS758755 A
9.3.5
REC615 and RER615
Technical Manual
between the high- and low-voltage sides, the angle adjustment can be used to meet
synchronism.
GUID-AD453DCE-B54E-4A95-AC05-5A153E08AEBE V1 EN
Figure 322: Angle difference when power transformer is in synchrocheck 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 U_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
SECRSYN with the Phase shift setting.

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
Section 9
Control functions
625