User guide

47
IM 12D08N05-01E
A
APPENDICES
B. Calculation of temperature coefficient factor
(with two known conductivity values at different temperatures)
Measure the conductivity of the liquid at two temperatures, one below the reference and above
thereferencetemperaturewiththetemperaturecoefficientsetto0,00%/°Candusethefollowing
equationtocalculateatemperaturecoefficient(α).
K
T
K
ref
=
1+α ( T - T
ref
)
K
2
- K
1
α
=
K
1
( T
2
- T
ref
) - K
2
( T
1
- T
ref
)
K
1
K
2
K
ref
=
=
1+α ( T
1
- T
ref
)
1+α ( T
2
- T
ref
)
K
1
(1 + α ( T
2
- T
ref
)) = K
2
(1 + α ( T
1
- T
ref
))
K
1
· α ( T
2
- T
ref
) - K
2
· α ( T
1
- T
ref
) = K
2
- K
1
Where T
1
, T
2
: liquid temperature (°C)
K
1
: conductivity at T 1 (°C)
K
2
: conductivity at T 2 (°C)
Figure 11-1. Conductivity
Calculation example
Calculate the temperature coefficient of a liquid from the following data.
Conductivity124.5µS/cmataliquidtemperatureof18.0°Canda
conductivity 147.6 µS/cmataliquidtemperatureof31.0°C.
Substitutingthedataintheaboveformulagivesthefollowingresult.
147.6 - 124.5
x 100= 1.298 %/C
α =
124.5(31.0 - 25) - 147.6(18.0 - 25)
SetthetemperaturecoefficientintheSC450Gconverter.