Ashcroft ATE-2, Operation And Maintenance Manual

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37
The Percent Error Function allows the user to display the output
from a device under test in terms of percent error of the full scale
range of that device. This function applies to the calibration of
both temperature and pressure devices. Percent error mode
eliminates the need for manual calculations to determine the level
of accuracy of the device under test.
The HHC is capable of comparing two measurements in several
configurations
• Pressure or temperature input to current output device, such as
a transducer with 4-20 mA output
• Pressure or temperature input to voltage output device, such as
a transducer with 0-10 Vdc output
• Pressure to pressure device, such as a pneumatic controller
• Current input to pressure output device such as a pressure
regulator with 4-20 mA input signal
All input and output parameters can be programmed by the
operator.
Datalogging is possible while using the HHC in Percent Error
Mode. Datalogs will include only the actual values measured. Dat-
alogs will not include the percent error calculation as displayed
on the HHC screen.
For example, if the HHC is being used to calibrate a 0-100 psi
transmitter with 4-20 mA output the HHC will display the following
data:
• Input pressure, as measured by Quick-Select pressure module
in selected engineering units that is being applied to the device
under test. This is the standard against which the device under
test is being compared.
• Output, from the transducer under test in output units (milli-
amps)
• Percent error, calculated by comparing the theoretical milliamp
output of the device under test based on the measured pres-
sure reading, against the actual measured output of the device
under test. The HHC will indicate whether this error is positive
or negative as compared to the theoretical output.
If 50.00 psi is applied to a 0-100 psi pressure transducer with a
1-5 Vdc output, the theoretical output will be 3.000v. If the mea-
sured output from the transducer is 3.015v, the HHC will display
the following:
% Error terms
Input refers to any pressure or electrical signal input to both the
device under test and the pressure or temperature module in the
HHC.
Input Channel refers either to a pressure or temperature module
installed in the base unit (CH1 or CH2), or a voltage or current
signal connected to the common and input jacks.
Input Range refers to the numeric full scale range of the input
parameter. It is not necessary to program an engineering unit for
the input range. For example, a pressure transducer with a mea-
surement range of 0 to100 psi. The engineering unit is automati-
cally determined by the channel selected (pressure, temperature,
voltage or current).
SECTION 15 h. PERCENT (%) ERROR FUNCTION
50.000
In(PSi) Out(volts)
% error
2.423
0.38