Vaisala HMT370EX - Configuring Calculation Coefficients

2. If you are using Insight PC software:
a. Connect to Insight PC software: see Connecting to Insight PC software (page 103).
Note that configuring these settings requires using Insight in Advanced
Mode.
b. Select > Configure Device > Filtering.
c. To enable the default filtering factor (13 second moving average (T90)), set the
Filtering on/o selection to ON and select Save.
d. If you want to enter a custom filtering factor, set the Extended filtering on/o
selection to ON, enter the custom value into the Filtering factor field, and select Save.
9.4 Configuring calculation coecients
You can configure a compensation value for the molar mass of the ambient gas and oil-specific
coecients to HMT370EX with Vaisala Insight PC software. The oil-specific coecients (Oil A
and Oil B) are only applicable for the HMP378F oil measurement probe option.
Note that the default calculation coecients (see HMP378F calculation model
with average oil coecients (page 117)) are valid for mineral transformer oil.
Note that calculation coecients can only be configured with Insight PC software.
Configuring these settings requires using Insight in Advanced Mode.
To enter calculation coecient values with Insight:
1. Connect to Insight PC software: see Connecting to Insight PC software (page 103).
2. Select
> Configure Device > Calculation coecients.
3. Enter the calculation coecients (Molar mass of gas, Oil A, or Oil B) as applicable in their
respective fields and select Save.
9.4.1 HMP378F calculation model with average oil coecients
The oil moisture calculation model in HMP378F probes is based on average water solubility
behavior of transformer oils. The ppm
w
output is calculated as follows:
ppm
w
= a
w
× 10
(A/(T+273.15)+B)
a
w
water activity
A, B coecients (average or oil specific)
T temperature (°C)
Chapter 9 – Environmental compensation and measurement settings
117