|
 Based
on both the Model 4040 Frequency Instrument
and the Model 4078 AC Strain Gage Instrument,
the Model 4K/HP is a two-channel instrument for accurate measurement of TORQUE,
RPM, and HORSEPOWER.
Like
the analog input of the 4078, the 4K/HP's torque input channel is
of phase-sensitive carrier-amplifier design, and accepts a
force-measurement signal from a conventional strain gage transducer with a
4-arm bridge of nominal 350 Ω or higher, and a full-scale range of
0.75, 1.50, or 3.00 mV/V.
Like
the analog input of the 4040, the 4K/HP's frequency (or RPM) input
channel accepts a pulse signal from a tachometer pickup, turbine flowmeter,
transistor or logic-circuit driver, "zero-velocity" (true
digital output) sensor, or similar frequency-generating transducer.
Reported
by a separate data channel, a "live" horsepower value is
continuously calculated from the "tared" readings of these two
inputs (under the 4K/HP's "standard configuration," the tare
offset for the frequency channel is always zero).
|
Functions
Provided by the
MODEL 4K/HP "STANDARD
CONFIGURATION"
(for
a complete listing of the configuration, click
here) |
 |
A
preprogrammed tare function for the TORQUE input may be activated by front-panel
button (under the 4K/HP's "standard configuration,"
the tare offset for the frequency channel is always zero) |
|
Via
front-panel buttons, you can call to display either of the
two "live" tared inputs (TORQUE or RPM), or the
current HORSEPOWER value derived from these inputs |
|
For
either tared input or for the horsepower channel, you can also
display the maximum (most positive) value since last
reset, the minimum (least positive) value since last
reset, or the existing net difference between these
maximum and minimum values |
|
The "MAX" and "MIN" functions can be reset by a front-panel
button |
|
Three
of the 4K/HP's Logic I/O functions are logic outputs
tied to the "OK" limit zone of the tared TORQUE
channel, the tared RPM channel, and the HORSEPOWER channel,
respectively. That is, each port will be at a Logic 1
state when and only when the corresponding data channel is not
violating any of its predefined limit setpoints. (The
remaining five Logic I/O Ports are for internal use only.) |
|
The
4K/HPs ±10
VDC analog output is not initially tied to any specific
channel |
|
For
a typical 4K/HP operation, see Engine
Dynamometry.
Horsepower
Instrument Specifications [Top 
]
(Click
here for
4000 Series General
Specifications; see also
the statement
on Daytronic accuracy specifications)
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|
TORQUE
Input
|
|
Input
Type |
Conventional
4-arm strain gage bridge, nominal 350 Ω or higher |
|
Input
Range (full-scale) |
0.75,
1.50, or 3.00 mV/V* |
|
Excitation
Supplied |
Regulated
3 VAC (RMS) at 3280 Hz; 75 mA (RMS) maximum |
|
Amplifier |
AC-coupled
demodulator with user-settable phase and symmetry controls |
|
Normal-Mode
Range |
±12
mV-AC (RMS) operating; ±8 VDC without instrument damage |
|
Common-Mode
Range |
±0.8
VDC operating; ±8 VDC without instrument damage |
|
Common-Mode
Rejection Ratio |
Infinite
at DC and 60 Hz; -80 dB at 1 kHz; -60 dB at 3 kHz |
|
Input
Impedance (Differential and Common-Mode) |
10 MΩ |
|
Offset |
Initial:
±3% of full scale
Vs. Temperature: ±0.005% f.s./°C
Vs. Time: ±0.002% f.s./month
|
|
Gain
Accuracy |
±0.025%
of full scale ± 1 count LSD, typical, following calibration** |
|
Gain
Stability |
Vs.
Temperature: ±50 ppm/°C
Vs. Time: ±20 ppm/month
|
|
Analog
Filtering |
|
Filter |
3-pole
modified Butterworth; -3 dB at 7.5 Hz; -60 dB at 60 Hz
|
|
Step
Response Settling Time (Full-Scale Output) |
To
1% of final value: 300 ms
To 0.1% of final value: 450 ms
To 0.02% of final value: 600 ms
|
|
FREQUENCY
(RPM)
Input
|
|
Input
Type |
Any
AC or unipolar pulse signal, grounded or floating, irrespective of
waveform |
|
Frequency
Range |
From
5% to 100% of 250, 500, 1000, or 2000 Hz; from 2% to 100% of 4, 8,
16, or 32 Hz |
|
Threshold
Level |
Selectable
to accommodate signals from 250 mV to 100 V |
|
Excitation
Supplied (for "Zero-Velocity" sensors) |
Nominal
±5 VDC; ±50 mA maximum |
|
Normal-Mode
Range |
±100
V operating; ±200 V without instrument damage |
|
Common-Mode
Range |
±100
V operating and without instrument damage |
|
Common-Mode
Rejection Ratio |
-120
dB at 60 Hz; -60 dB at 1 kHz |
|
Input
Impedance |
Differential:
400 kΩ
Common-Mode: 100 kΩ |
|
Offset |
Initial:
±0.05% of full scale
Vs. Temperature: ±25 ppm/°C
Vs. Time: ±20 ppm/month
|
|
Gain
Accuracy |
±0.02%
of full scale ± 1 count LSD |
|
Gain
Stability |
Vs.
Temperature: ±40 ppm/°C
Vs. Time: ±20 ppm/month
|
|
Analog
Filtering |
|
Filter |
5-pole
modified Butterworth, with characteristics selectable as
"1," "2," or "3," as follows:
(1) -3 dB at 10 Hz; -60 dB at 75 Hz
(2) -3 dB at 5 Hz; -60 dB at 35 Hz
(3) -3 dB at 2.5 Hz; -60 dB at 20 Hz
|
|
Step
Response Settling Time (Full-Scale Output) |
(1)
To 1% of final value: 40 ms
To 0.1% of final value: 90 ms
To 0.02% of final value: 150 ms
(2)
To 1% of final value: 65 ms
To 0.1% of final value: 135 ms
To 0.02% of final value: 220 ms
(3)
To 1% of final value: 150 ms
To 0.1% of final value: 30 ms
To 0.02% of final value: 450 ms
|
|
Ripple
and Noise |
Readings
are within the stated accuracy from
(1) 30% to 100% of the frequency range in use
(2) 15% to 100% of the frequency range in use
(3) 10% to 100% of the frequency range in use
|
|
* 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/HP, if zero unbalance exceeds 20% of full
scale.
** Initial (uncalibrated) inaccuracy may be as great as ±3% of full
scale. Maximum error that could occur upon replacement of the Model
4K/HP not followed by calibration is ±6% of full scale. |
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