ABB UNITROL 1020 - Page 55

 Chapter 3 - Device Overview
UNITROL 1020 User Manual 3BHS335648 E82 47
Regulator
E
SM
Command
UNET
Fbias
Speed Controller
Setpoint fSP = fNom
UM
Sync
Setpoint
CB
T
Synchrocheck
Figure 3-8 Typical application for Synchronization.
CAUTION!
Synchronization should never be performed by calculation only. All
measurements shall be confirmed on site before synchronization takes
place.
The power circuit breaker (CB) must not be closed unless both
voltages are at least approximately synchronous (coincident).
Otherwise, this may result in faulty line operation, loading of the
synchronous machine and, in extreme cases, damage to the
synchronous machine.
A separate synchrocheck relay might be used to secure the right
operation. For further information please contact ABB.
Measuring and Matching
The values are obtained by the two measurement signals UNET and UM
 Voltage difference (amplitude)
 Slip (frequency difference)
 Phase-angle difference
The voltage matching function gives the adjusting value to the internal voltage regulator
and the frequency matching function sends the analog signal Fbias to the turbine
regulator.
Monitoring and command generation
The command to close the breaker (CB) is released if all conditions are fulfilled.