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DIMENSIONS
THEORY OF OPERATION
The amplifier section of the W894A supplies an excitation of
1.4 V-ac (440 Hz square wave) across Pins A and B of the
W894A's internal MS connector to the transducer. See the
Block Diagram. As the machine is tilted off the proper slope,
the rotor rotates with respect to the secondary coils. As the
rotor moves toward one secondary and away from the other,
the voltage induced in the coil toward the rotor is increased,
the opposite being true of the other secondary. At the full
10%-from-null slope (the rated maximum range), the voltage
across the secondary closer to the rotor is 5.3 V-ac, while the
other voltage is 4.2 V-ac.
ENVIRONMENTAL
OPERATING TEMPERATURE
-18° to 77° C (0° to 170° F)
STORAGE TEMPERATURE
-40° to 77° C (-40° to 170° F)
HUMIDITY
After being placed in a controlled atmosphere of 95%
humidity at 49° C (120° F) for 10 days, the W894A will
perform within specification limits.
RAIN
After being showered from all directions by a high
pressure hose down, the W894A will perform within
specification limits. This test fulfills NEMA 4 specifica-
tions.
Dimensions of the W894A in Millimeters (Inches).
3
The ac signals from the secondaries are applied to two
bridge rectifiers in the amplifier section, where each is
converted to dc. At null the voltages across both capacitors
are equal. When a change in secondary voltage is intro-
duced, the voltages across the capacitors are offset,
inducing a differential between the reference (which may be
a remote setpoint command) and the junction between the
capacitors. This differential serves as the positive or nega-
tive correction signal that is amplified and then supplied to
the servovalves to close the control loop. Control action
drives the machine to a position such that the sensor error
signal to the amplifier section is reduced to null.
VIBRATION
Withstands a vibration test designed for mobile equip-
ment consisting of two parts:
1.
Cycling from 5 to 2000 Hz in each of the 3 axes.
2.
Resonance dwell for one million cycles for each
resonance point in each of the 3 axes.
SHOCK
50 g's for 11 milliseconds. Three shocks in both direc-
tions of the 3 mutually perpendicular axes for a total of
18 shocks.
WEIGHT
3.4 Kg (7 pounds, 8 ounces)
DIMENSIONS
See the Dimension Drawing.
1182
BLN-95-8974-5
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