![ABB 266 MODBUS User Manual Download Page 73](http://html.mh-extra.com/html/abb/266-modbus/266-modbus_user-manual_5388073.webp)
5 Service and maintenance
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB
| 65
Setting the measurement bias
Removing offsets
An important part of device installation is removing the offsets that may occur during shipment, handling, positioning, or other
sources.
Examples of installation issues that could cause a zero shift include: a slightly inclined mounting position, different liquid
columns in the differential pressure lines, and remote seals.
IMPORTANT NOTE:
For accurate correction, the transmitter must be allowed to acclimate to the surrounding
temperature and achieve operating temperature (Operating temperature is achieved approximately 5 min after
power is applied). The acclimation process may also be completed within the warm up period.
Standard acclimation time: 1 minute for each 1 °C difference at start-up
For example:
Acclimation time (15 minutes)
= Application sight temperature (30° C)
less transmitter temperature (15° C).
Optimum warm-up time (20 minutes)
= Operating temperature (5 minutes)
plus acclimation time (15 minutes)
The correction must also be made at zero flow (DP = 0).
To remove the offsets, use the bias options in the Device Setup menu (Table 15).
Table 15: Device menu
Menu
Submenu 1
Submenu 2
Selections or Description
Device Setup
Set Diff. Press
Units
Pa
inH2068F
kg/cm2
Mpa
inH2060F
mmH2068F
bar
inH204C
ftH2068F
PSI
Torr
inHgOC
kPa
Atm
mmHgOC
mbar
g/cm2
Lower Range Value
Upper Range Value
Damping
Set Diff. Press Bias
Set DP To Zero
Applies a bias to make the current displayed
value equal zero
Set DP To value
Applies a bias to make current displayed value
equal the entered value
Reset DP Bias
This removes the user saved bias
Set Static Press.
Units
Pa
inH2068F
kg/cm2
Mpa
inH2060F
mmH2068F
bar
inH204C
ftH2068F
PSI
Torr
inHgOC
kPa
Atm
mmHgOC
mbar
g/cm2
Lower Range Value
Upper Range Value
Device Setup, Cont.
Set Static Press., Cont.
Damping
Set Static Press. Bias
Set SP To Value
Applies a bias to make current displayed value
equal the entered value
Summary of Contents for 266 MODBUS
Page 163: ......