ABB SYNCHROTACT® 5 Range of applications

SYNCHROTACT® 5

Range of applications

Synchronizing devices are widely used in power stations or

industrial installations with their own power generating facilities,

where the generators need to be paralleled with an island line

or a public line, or in power distribution systems.

Power circuit breakers may only be closed if both voltages are

approximately synchronous (coincident). Otherwise, faults in

line operation, loading of the generators and, in extreme cases,

damage to the generators can result.

SYNCHROTACT® 5 performs these functions safely and reliably,

whether as a monitoring element for manual paralleling or as

an independent fully-automatic synchronizing device.

Principle of operation

The synchronizing and paralleling process can be divided

into the following blocks

Measuring

Voltage difference ΔU (amplitude), slip s (frequency diffe

rence), and phase-angle α, are all required for paralleling.

These values are formed from the two measurement signals

U1 and U2 (see illustration, left).

Matching

Voltage and frequency matching functions reduce the voltage

difference ΔU, and slip s by sending adjusting pulses to the

voltage or turbine regulators.

Monitoring of paralleling conditions

This function compares the actual values with their set

maximum values and releases paralleling (CHK RELEASE) if

all conditions are fulfilled simultaneously.

Command generation

The command generation calculates the necessary lead angle

αv, by which the paralleling command must be advanced

due to closing time delay. The action ensures that the main

contacts close at precisely the right time. If α reaches αv at

the same time as paralleling release (CHK RELEASE), the

command is issued. Under synchronous conditions, ie,

permanent paralleling release during the adjustable monitoring

time, tsup, the CMD is also issued without taking the lead

angle into consideration.

Synchrocheck mode (paralleling monitoring)

In synchrocheck mode, only the measuring and monitoring

function blocks are active. The output relay is closed during

paralleling release.