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Based
on the Model 4077 DC Strain Gage Instrument,
the Model 4K/WT-77 is a complete weighing system in a compact instrument
package, with the full analog ±peak
capture capability of the 4077.
The
4K/WT-77 typically connects to an industrial load cell or submersible
differential pressure transducer (a remote junction box can be used
to sum multiple transducer inputs). Internal 15-segment
linearization can be used to accommodate the irregularity of a fluid
container.
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Functions
Provided by the
MODEL 4K/WT-77 "STANDARD
CONFIGURATION"
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Bargraph
indication of UNDERWEIGHT and OVERWEIGHT setpoints |
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Front-panel
buttons for ZERO and TARE functions |
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Front-panel
buttons for display of either GROSS WEIGHT or NET
WEIGHT |
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Front-panel
button for initiation of HARD-COPY OUTPUT
("PRINT") |
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Front-panel
button for computation and display of TIME RATE OF CHANGE (Δy/Δt) |
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Front-panel
"ON ZERO" indication |
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Isolated
limit-controlled logic outputs for process control |
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Scaled
±10
VDC analog output for strip-chart recording, etc. |
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As
with all 4000 Series instruments, the optional Model
10P25D Operator's Keyboard allows easy user interaction during
run-time operation.
For
a typical 4K/WT operation, see Batch
Weighing.
Industrial
Weighing Instrument Specifications [Top 
]
(Click
here for
4000 Series General
Specifications; see also
the statement
on Daytronic accuracy specifications)
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Number
of Inputs |
One |
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Input
Type |
Conventional
4-arm strain gage bridge, nominal 120 Ω or higher NOTE:
1/4- and 1/2-bridge gage configurations can be accomplished by means
of the Model 10CJB-2 Bridge Completion Card,
or by equivalent external bridge completion circuitry supplied by the
user.
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Input
Range (full-scale) |
1.5
or 3.00 mV/V* |
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Excitation
Supplied |
Selectable
5 or 10 VDC, nominal; ±80 mA maximum |
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Normal-Mode
Range |
±50
mV peak operating; ±8 V without instrument damage |
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Common-Mode
Range |
±0.25
V peak operating; ±8 V without instrument damage |
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Common-Mode
Rejection Ratio |
-90
dB at DC; -120 dB at 60 Hz, 1 kHz, and 3 kHz |
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Input
Impedance (Differential and Common-Mode) |
Greater
than 100 MΩ |
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Offset |
Initial:
±0.02% of full scale
Vs. Temperature: ±20 ppm/°C
Vs. Time: ±10 ppm/month
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Gain
Accuracy |
±0.02%
of full scale ± 1 count LSD, typical, following calibration** |
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Gain
Stability |
Vs.
Temperature: ±50 ppm/°C
Vs. Time: ±20 ppm/month
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Analog
Peak Memory Decay Rate |
Does
not exceed 0.4% of full scale/second (e.g., with full scale of 20000
counts, decay rate will not exceed 8 counts/100 msec) |
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Analog
Filtering |
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Filter |
3-pole
modified Butterworth; -3 dB at 20 Hz; -60 dB at 220 Hz
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Step
Response Settling Time (Full-Scale Output) |
To
1% of final value: 60 ms
To 0.1% of final value: 80 ms
To 0.02% of final value: 125 ms
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*
Since channel zeroing is by digital techniques, no input balance control
is provided. The allowable input range, therefore, must include an initial
unbalance (which, in commercially produced strain gage transducers, is
negligible). Other transducers may have to be externally trimmed to
be used with the Model 4K/WT-77, if zero unbalance exceeds 20% of full scale.
**
Initial (uncalibrated) inaccuracy may be as great as ±0.05% of full
scale. Maximum error that could occur upon replacement of the Model
4K/WT-77 not followed by calibration is ±0.1% of full scale. |
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