-
frequency (i.e.: the output for a 3 Hertz difference is larger than that for a 1 Hertz difference.) If the
Reset jumper is installed to provide internal operation, the signals will continue being output until the
phase angle is within the front panel setting. If the Reset function is being controlled externally, the
correction signals will continue until the external reset contacts are closed.
(b) If the output type is a contact closure, then the contacts are closed at any phase angle
greater than the front panel setting and are open only if the phase angle is 0°or if the phase angle is
within the front panel setting for acceptable phase conditions.
(2) Voltage Correction Option.
An optional voltage option may be installed. When this option
is installed, it operates as follows:
(a) If the output is a summing point type, the Synchronizer outputs a "bipolar" correction
signal that is proportional to the amount of voltage difference (i.e.: the larger the voltage difference
between the bus voltage and the generator voltage, the larger the correction signal). If the Reset
jumper is installed to provide internal operation, the signals will continue being output until the
difference voltage is within the front panel setting. If the Reset function is being controlled externally,
the correction signals will continue until the external reset contacts are closed.
(b) If the output type is a contact closure, then the contacts are closed at any difference
voltage greater than the front panel setting and are open only if the difference voltage is within the
front panel setting for acceptable synchronizing conditions.
(3) Dead Bus Connection Option.
This option will allow a breaker closure to occur even
though the bus is dead or extremely low (i.e.: a maximum of 10 - 50 Vac is present).
a. Power Supply Theory of Operation. Either the oncoming generator or the bus voltage is fed to
the Synchronizer Power Supply. The Power Supply steps the voltage down and rectifies it to provide
a +12 Vdc and a -12 Vdc output.
b. Basic Unit Theory of Operation.
(1) Generator and Bus Sensing.
The oncoming generator and bus voltages are monitored
and processed by the Generator Sensing and Bus Sensing Circuits. The outputs of these circuits
are applied to the 0.1 Hertz Frequency Difference Comparator, the Phase Angle Comparator, and
the Voltage Difference Comparator. The Sensing Circuit outputs are also applied to the following
Option Circuits: Dead Bus, Frequency/Phase Matching, and Voltage Matching.
(2) 0.1 Hertz Frequency Difference Comparator.
The 0.1 Hertz Frequency Difference
Comparator compares the frequencies of the bus and the oncoming generator. IF the frequencies
are within 0.1 Hertz of each other, an output signal is applied to the Gating Network.
(3) Phase Angle Comparator.
The Phase Angle Comparator compares the phase angle of
the bus to that of the oncoming generator. When the phase angle difference becomes less than ±5°
to ±20°(as selected by the front panel potentiometer), the resulting output signal will be applied to
the Gating Network.
(4) Voltage Difference Comparator.
The Voltage Difference Comparator compares the
voltage of the bus to that of the oncoming generator. When the voltage difference becomes less
than ±5% to ±15% (as selected by the front panel potentiometer), the resulting output signal will be
applied to the Gating Network.
(5) Gating/Time Delay Circuitry.
When the 0.1 Hertz Frequency Difference Comparator
output, Phase Angle Comparator output, and the Voltage Difference Comparator output are all
present at the Gating Circuitry input, the Time Delay Circuit will be triggered to start counting down.
All three inputs must be present for at least 0.75 seconds before the Closing Contact Circuit is
2-2. SYNCHRONIZER THEORY OF OPERATION (Refer to Figure 2-2)
Courtesy of NationalSwitchgear.com
