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Description

The SPM-A Synchronizer biases the speed of an off-line generator set so that the frequency and phase match those of another generator or the utility bus. Then it automatically issues a contact closure signal to close the circuit breaker between the two when frequency and phase are matched within limits for a specified match-up time. The SPM-A is a phase-locked-loop synchronizer and strives for a perfect match of frequency and phase.

The SPM-A Synchronizer with voltage matching generates additional raise and lower signals (relay contact closures) to the generator's voltage regulator. Voltages must match within the SPM-A's tolerance before breaker closure occurs. For single-unit synchronization, installation of one synchronizer on each generator allows each unit to be individually paralleled to the bus. For multipleunit synchronization, one synchronizer can synchronize up to seven paralleled generator units simultaneously to another bus. Both synchronizers versions have three output options: high impedance, low impedance, and EPG.

Select the high impedance output for single-unit synchronization when the engine is controlled by a Woodward 2301 control. Select the low impedance output for single-unit synchronization when the engine is controlled by a Woodward 2301A, 2500, or Electrically Powered Governor (EPG) control through a Generator Load Sensor. Use the EPG output when using a Woodward EPG control without load sensing. Both units have the following features:

 120 or 208/240 Vac input

 10 degree phase window

 1/8, 1/4, 1/2, or 1 second dwell time (internally switch selectable, factory set for 1/2 second) The SPM-A Synchronizer with voltage matching has a 1% voltage match as standard. See the part number chart for other options.

Theory of Operation

This section describes the general theory of operation of the two versions of the SPM-A Synchronizer. Figure 1-1 shows the SPM-A Synchronizer with voltage matching. Figure 1-2 shows a typical synchronizer system block diagram. Figure 1-3 shows a functional block diagram of the synchronizer.

Synchronizer Inputs

The SPM-A Synchronizer checks the phase angle and frequency of the bus and an off-line generator which is to be paralleled. The voltage inputs from the bus and generator are first applied to separate signal conditioner circuits. Each signal conditioner is a filter which changes the shape of the voltage input signals so they can be accurately measured. A phase offset potentiometer in the signal conditioner circuit is adjusted to compensate for phase errors. (This adjustment is factory set with identical bus and generator inputs. It should be readjusted only where a phase offset has been caused through the line transformers of the installation.) The signal conditioners also amplify the bus and generator signals and apply them to the phase detector.

Operating Modes A user-installed mode switch (single-pole, four-position) controls the relay driver.

The switch must be wired to synchronizer contacts 10 through 13 (see the plant wiring drawing). The four positions are OFF, RUN, CHECK, and PERMISSIVE.