DSLC Digital Synchronizer and Load Control
Manual 02007
60
Woodward
Chapter 4.
Synchronizer Description
Introduction
Synchronization, as normally applied to the generation of electricity, is the
matching of the output voltage wave form of one synchronous alternating current
electrical generator with the voltage wave form of another alternating current
electrical system. For the two systems to be synchronized and connected in
parallel, five conditions must be considered:
•
the number of phases in each system;
•
the direction of rotation of the phases;
•
the voltage amplitudes of the two systems;
•
the frequencies of the two systems ;
•
the phase angle of the voltage of the two systems.
The first two conditions are determined when the equipment is specified,
installed, and wired. The synchronizer matches the remaining conditions
(voltage, frequency, and phase) before the paralleling breakers are closed.
Functional Description
This section describes how generator and bus matching occurs and how all
conditions are verified by the synchronizer functions. Figure 4-1 shows the
functional block diagram of the synchronizer for reference during the following
descriptions.
Operating Modes
The operation of the synchronizer is determined by the mode switch as shown in
Figure 4-2. The four modes are Off, Run, Check, and Permissive. When the
switch is off, the synchronizer is out of operation.
Run mode allows normal synchronizer operation and breaker closure signals.
The speed bias signal (explained below) is maintained throughout the breaker
closure signal. When the specified closure signal time has elapsed or the CB
(circuit breaker) aux contact closure signal is received at terminal 47, the
synchronizer is disabled. The synchronizer may optionally be reset automatically
when the generator is disconnected from the bus.
Check mode allows normal synchronizing and voltage matching, but does not
issue a breaker closure signal.
Permissive mode enables the synch-check function for proper synchronization,
but synchronizer operation does not affect the engine's speed or generator
voltage. If phase, frequency, and voltage are within proper limits, the
synchronizer issues the breaker closure command.