3-4
BE1-25A Functional Description
9146600990 Rev M
MICROPROCESSOR CIRCUITRY
The microprocessor, with the associated memory and decoding logic, performs all calculations, makes all
decision, and controls the display and output circuitry. These functions are for the most part, determined by
the software in the manner illustrated by the flow diagram of Figure 3-3.
Returning to Figure 3-2, a crystal oscillator provides a precise time reference for determining frequency and
phase relationships.
The power up/down reset logic (at the lower left corner) monitors the internal logic voltages. If any of the
voltages fall below a critical threshold, the microprocessor is placed in a park mode. All decision making
is then inhibited until such time as all vital voltages return to normal. (Because all settings and vital,
programming instructions are held in non-volatile memory (EEPROM), and are not erased if power is lost.)
Microprocessor operation is monitored by the watchdog circuitry. If some transient condition has disrupted
the normal pattern of operation, the watchdog operates the alarm output, resets the microprocessor and
initializes the program. The reset restarts the microprocessor. After the third such reset operation (perhaps
indicative of some hardware failure), the microprocessor is stopped and shuts down the entire unit. This
condition remains until operating power is disconnected, then reapplied. (An inoperative microprocessor
usually appears as a display that is frozen and
)
probably
)
inappropriate or meaningless.)
OUTPUTS
Again referencing Figure 3-2, the Output Drivers provide the interface required between the logic circuits
and the final outputs, which are the LED indicators and the output relays. The Breaker Close relay provides
a normally open contact. The other output relays are of the plug-in type, and are only incorporated into the
unit upon the addition of the relevant option(s). Note that these supplementary relays provide both normally
open and normally closed contacts for each function represented. (For the terminal numbers of these
contacts see the last page of Section 4.)
OPTIONS
The various options available for the BE1-25A Auto-Synchronizer Relay are described on the following
pages. Note that they are grouped into four categories:
Voltage Acceptance, Voltage Matching, Frequency
Matching, and Dead Bus. Only one option from each category can be used at one time.
The basic Synchronizer may be upgraded to Automatic Synchronizer status by incorporating one of the
voltage matching options and/or one of the frequency matching options. This may be accomplished at any
time
)
i.e., at original purchase or at any time thereafter.
Legend
for Figure 3-3.
ADVANCE ANGLE
-
Number of degrees that the
close breaker
signal must precede actual
closure of the breaker so that the closure occurs at (or very close to) zero
degrees of phase difference.
BF
-
Bus frequency.
CLOSE BREAKER
-
Represent the closure of the BE1-25A output contact to provide closing
current to the breaker.
DEAD BUS
-
A condition where the bus voltage is less than the setting of module D1,
VOLTS control.
GF
-
Generator frequency.
GV
-
Generator voltage.
MAX SLIP
-
Maximum slip frequency setting.
F
S
-
Slip frequency.
UV
-
Undervoltage Setting
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