
3
Description of
operation
The synchro-check module SPCU 3D45 in-
cludes two identical operation stages and both
stages are provided with a synchro-check and a
voltage-check function. The synchro-check re-
lay module measures three different voltages: bus
voltages U1 and U2 and line voltage U3. The
operation stage 1 checks the closing conditions
between bus voltage U1 and line voltage U3 and
operation stage 2 similarly checks the closing
conditions between bus voltage U2 and line
voltage U3. Figure 1 shows a simplified block
diagram of the synchro-check module SPCU
3D45 with measured bus and line voltages and
check functions.
Fig. 1. A simplified block diagram of synchro-check module SPCU 3D45 and check functions.
Synchro-check
function (SC13)
U1
U2
U3
CB13
CB23
Synchro-check
function (SC23)
Voltage-check
function (VC13)
Voltage-check
function (VC23)