Honeywell STT850 Series - Stress Life; Table 20 - Minimum ET Diagnostics

Page 88 STT850 Series HART/DE Option User’s Manual Revision 4.0
Table 20 – Minimum ET Diagnostics
Min ET Limit
Parameter
Description
Electronics Temperature (ET) lower
operating limit from specification.
Units are same degree units as has
been selected for SV (Secondary
Variable).
Set-up
None.
ET Lower Limit
for Stress
Condition
Description
Actual limit used in “Time Below Limit”
and “Time Since Last Event”. Value is
equal to “Min ET Limit” plus 10% of
limits range.
Example
Electronics Temperature range is -40C
to 85C for a total of 125C.
“ET Lower Stress Limit” -40C + 10%
of 125C = -27.5C.
Set-up
None – calculation is automatic.
Min ET Value
Parameter
Description
Lowest Electronics Temperature ever
experienced by the device.
Units are same degree units as has
been selected for SV (Secondary
Variable).
Set-up
None.
NVM
Update every 8 hour.
Time Below
Lower Stress
Limit
Parameter
Description
Accumulation of minutes that device’s
Electronics Temperature has been
below the value of “ET Lower Stress
Limit”.
Set-up
None.
NVM
Backup once each 8 hour period
Time Since
Last ET Down
Method
Description
Time that has passed since the last
time device’s Electronics Temperature
has passed below the value of “ET
Lower Stress Limit” (in days, hours, and
minutes).
Set-up
None.
NVM
Backup once each 8 hour period
8.2.5 % Stress Life
% Stress Life
Parameter
Description
Percent of service life spent in stressful
conditions. Indicates the % of service
life where electronics temperature is
within 10% of respective range limits.%
of Service life spent either in 10% of
lower limit range or 10% of upper limit
range.
Set-up
None.
NVM
Backup once each 7.5 hour period