7-6
BE1-25A Relay Differences
9146600990 Rev M
The differentiator produces a dc voltage proportional to the rate of change of the input triangular waveform,
and outputs this voltage to the breaker time compensation circuit, the in sync/in phase circuit, the
comparator and the precision full wave rectifier. The dc output of the precision full wave rectifier is further
smoothed by the sample and hold circuit. The sample and hold circuit output is input to the in sync/in phase
circuit and to the slip frequency comparator.
If the input signal to the slip frequency comparator exceeds the front panel SLIP FREQUENCY adjustment
setting (i.e. the reference), an inhibit signal is delivered to the output gate and the front panel FS HIGH
indicator illuminates. When the input slip frequency signal is less than the front panel SLIP FREQUENCY
setting, an enable signal is sent by the inhibit gate to the in-sync output gate to permit breaker closure when
the other conditions are met.
If the phase angle is greater than 40
E
, the 40
E
inhibit sync circuit outputs an inhibit signal to the inhibit gate.
The lockout circuit will generate an inhibit signal such that if the generator breaker opens within 15 seconds
after closing, the synchronizer will not attempt to reclose the relay. The lockout circuit outputs are sent to
the sync circuits, the timer, and to any options. In addition, the front panel LOCKOUT indicator will illuminate.
This function may be reset by use of the LOCKOUT RESET switch, or by an external contact closure. A
circuit-board-mounted switch (S2 of the circuit board) can be used to disable or enable this function.
The inhibit gate receives the generator frequency greater than bus frequency (GF>BF) signal, the
differentiator output, and any option outputs. These are compared, and when the generator frequency, bus
frequency, and phase angle are within limits, an enable signal is output to the in sync output gate. This is
acknowledged by the illumination of the SYNC indicator.
The breaker time timer will start timing as soon as the close signal is sent to the generator breaker. The
period of this timer is adjusted by the BREAKER CLOSING TIME control. When the timer times out (at 0
E
),
a reset signal is output to the in sync output gate to remove the close breaker signal, and a remove correc-
tion signal is output to the V and F options.
When the in sync/in phase circuit inputs (from the differentiator circuit and the sample and hold circuit)
indicate less than 0.008 Hz frequency difference and less than a 3
E
±1
E
phase angle difference, the timer
will time out provided there are no inhibits present. After two seconds, a 100 msec pulse is output to the
relay driver to close the controlled breaker.
The sensed bus voltage is rectified and output to the comparator shown at bottom left of Figure 7-4, where
it is compared to a reference level that is controlled at the front panel. If the bus is below the front panel
setting, a dead bus signal is output.
Sensed generator voltage is rectified and output to two comparators shown at bottom right of Figure 7-4.
One comparator compares the generator voltage to the front panel UNDERVOLTAGE INHIBIT ADJUST
reference. When the generator voltage is below the reference, it produces an undervoltage signal and
illuminates the UNDERVOLTAGE INHIBIT indicator. The other comparator compares the generator voltage
to a fixed reference. If the generator voltage is below the fixed reference, a dead generator signal is output.
An out-of-range signal (right center of Figure 7-4) is generated if the differentiator output indicates that the
bus and generator frequency difference is greater than a preset value, thereby inhibiting synchronization.
Calibration Instructions
Equipment Required
(1)
Two frequency-adjustable voltage sources for the generator and bus sensing inputs. Requires a
low-distortion output with a voltage range of 70-150 Vac, and a frequency that is adjustable in
0.005 Hz increments. (The use of less accurate sources will result in less accurate settings.)
(2)
Input power source capable of either 90-132 Vac at 50/60 Hz, or 70-150 Vdc.
(3)
Oscilloscope or counter for measuring pulse width.
(4)
Ac Voltmeter.
(5)
Synchroscope.
(6)
Switches or jumpers for enabling the 52b, GF>BF, GV>BV, and dead bus functions.
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