Beckhoff EPP3504-0023 Short Manual page 55

Under different conditions, user-specific adjustment is required.
Notes on calculation with the specification data:
The independent specification data can be divided into two groups:
• the data on offset/gain deviation, non-linearity, and repeatability, whose effect on the measurement
cannot be influenced by the user. These are summarized by Beckhoff according to the calculation
below, at "basic accuracy at 23°C".
• the specification data whose effect on the measurement can be influenced by the user, namely
◦ noise: effect can be influenced by sample rate, filtering and
◦ the temperature: effect can be influenced by control cabinet air conditioning, shielding, cooling,
etc.
The independent individual accuracy data are to be added quadratically according to the formula below in
order to determine the total measurement accuracy – if there are no special conditions that contraindicate a
uniform distribution and thus the quadratic approach (RSS – root sum squared method).
For measurement ranges where the temperature coefficient is only given as Tc
E : Offset specification (at 23°C)
Offset
E : Gain/scale specification (at 23°C)
Gain
E : Noise specification as a peak-to-peak value (applies to all temperatures)
Noise, PtP
MV : Measured value
FSV : Full scale value
E : Non-linearity error over the entire measuring range (applies for all temperatures)
Lin
E : Repeatability (applies to all temperatures)
Rep
Tc : Temperature coefficient offset
Offset
Tc : Temperature coefficient gain
Gain
Tc : Temperature coefficient of the box module
Terminal
ΔT : Difference between the ambient temperature and the specified basic temperature (23°C unless otherwise specified)
E : Error coefficient for ageing
Age
N : Number of years
Years
E : Theoretically calculated total error
Total
For example, if the following values are obtained at a determined measured value MV of 8.13 V in the 10 V
measurement range (FSV = 10 V) (N
• Gain specification: E
• Offset specification: E
• Non-linearity: E = 25 ppm
Lin
• Repeatability: E
Rep
• Noise (without filtering): E
• Temperature coefficients:
◦ Tc = 8 ppm/K
Gain
◦ Tc = 5 ppm
Offset
then the theoretical possible total measurement accuracy at ΔT = 12K for the basic temperature can be
calculated as follows:
or = ±0.0143.. %
FSV
EPP3504-0023
= 0):
Years
= 60 ppm
Gain
= 70 ppm
Offset FSV
FSV
= 20 ppm
FSV
= 100 ppm
Noise, PtP
/K
FSV
Version: 1.2
peak-to-peak
Product overview
:
Terminal
55