Commissioning
EL3773
125
Version: 2.5
6.10.2
Measuring error/ measurement deviation
The relative measuring error (% of the full scale value) is referenced to the full scale value and is calculated
as the quotient of the largest numerical deviation from the true value (‘measuring error’) referenced to the full
scale value.
The measuring error is generally valid for the entire permitted operating temperature range, also called the
‘usage error limit’ and contains random and systematic portions of the referred device (i.e. ‘all’ influences
such as temperature, inherent noise, aging, etc.).
It always to be regarded as a positive/negative span with ±, even if it is specified without ± in some cases.
The maximum deviation can also be specified directly.
Example
: Measuring range 0..10 V and measuring error < ± 0.3 % full scale value → maximum deviation ±
30 mV in the permissible operating temperature range.
Note
Lower measuring error
Since this specification also includes the temperature drift, a significantly lower measuring
error can usually be assumed in case of a constant ambient temperature of the device and
thermal stabilization after a user calibration.
This applies to analog output devices.
6.10.3
Temperature coefficient tK [ppm/K]
An electronic circuit is usually temperature dependent to a greater or lesser degree. In analog measurement
technology this means that when a measured value is determined by means of an electronic circuit, its
deviation from the "true" value is reproducibly dependent on the ambient/operating temperature.
A manufacturer can alleviate this by using components of a higher quality or by software means.
The temperature coefficient specified by Beckhoff allows the user to calculate the expected measuring error
outside the basic accuracy at 23 °C.
Due to the extensive uncertainty considerations that are incorporated in the determination of the basic
accuracy (at 23 °C), Beckhoff recommends a quadratic summation.
Example:
Let the basic accuracy at 23 °C be ±0.01% typ. (full scale value), tK = 20 ppm/K typ.; the accuracy
A35 at 35 °C is wanted, hence ΔT = 12 K
Remarks:
ppm
≙
10
-6
%
≙
10
-2
Summary of Contents for EL3773
Page 1: ...Documentation EL3773 Power Monitoring Oversampling Terminal 2 5 2018 03 13 Version Date...
Page 2: ......
Page 6: ...Table of contents EL3773 6 Version 2 5...
Page 39: ...Mounting and wiring EL3773 39 Version 2 5 Fig 29 Other installation positions...
Page 41: ...Mounting and wiring EL3773 41 Version 2 5 Fig 31 Block diagram...
Page 47: ...Commissioning EL3773 47 Version 2 5 Fig 38 Incorrect driver settings for the Ethernet port...
Page 147: ...Commissioning EL3773 147 Version 2 5 Fig 168 Confirming program start...
