Manual 37443A DSLC-2 - Digital Synchronizer and Load Control
© Woodward Page 141/226
Chapter 4.
Synchronizer Description
Introduction
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Synchronization is the matching of the output voltage wave form of one synchronous alternating current electric-
al 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
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This section describes how generator and bus matching occurs and how all conditions are verified by the syn-
chronizer functions.The examples shown in chapter “Measurement Connections (Examples)” on page 143 dem-
onstrate the AC measurement connection and configuration of the DSLC-2 system.
Operating Modes
The operation of the synchronizer is determined by the mode switch as shown in Figure 4-1. 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 70, 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. The breaker close command follows the GCB close hold time
(parameter 3416) setting. It does not stay closed for the complete time you are within the proper limits.
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