Vaisala MM70 - Manual (Page 33)

Chapter 4 _________________________________________ MENU OPERATIONS AND SETTINGS
If additional accuracy is needed, more information is found below in
the section Calculation Model with Oil Specific Coefficients on page
31.
Calculation Model with Oil Specific
Coefficients
For additional accuracy, oil specific calculation model can be used
both for mineral and silicon based oils. An oil sample has to be sent to
Vaisala for modelling. As a result, the specific coefficients (A and B,
see formula above) for the transformer oil are determined by Vaisala.
Using these coefficients the accuracy of measurements is increased.
The determination of specific coefficients shall be agreed with the
Vaisala representative.
The determined coefficients of the transformer oil can be programmed
to the MM70 by Vaisala or by a user according to the following
instructions.
NOTE Calculation Model with Oil Specific Coefficients is always needed
for silicone based oils.
Feeding the Coefficients to the
MI70 Memory
You can save in the memory specific coefficients for 4 different oils.
As shipped from factory the average coefficients are set for the
number 1 type (H2O oil: 1). Add your own coefficients as follows:
1. Open the MENU. First press the right arrow key, then press the
OPEN key.
2. Select Settings and press the right arrow key.
3. Select Measurement Settings and press the right arrow key.
4. If you want to keep the average coefficients under identification
number 1 (set in the factory), press the SET key and key in
number for the second oil type.
5. Select the A value (A:0.0000) and press the SET key.
6. Set the value A by using the arrow keys up/down/left/right,
press the OK key.
VAISALA _______________________________________________________________________ 31